Method and apparatus to enable csi reporting in wireless communication systems

ABSTRACT

A method for operating a user equipment (UE) comprises, in response to a condition being satisfied, selecting, from a full basis set, a basis subset comprising M l  bases for each layer l of a plurality of v layers; in response to the condition not being satisfied, selecting, from the full basis set, an intermediate basis set comprising N′ bases that are common among the plurality of v layers, and selecting, from the selected intermediate basis set, the basis subset comprising M l  bases for each layer l of the plurality of v layers; transmitting, to a base station (BS), for each layer l of the plurality of v layers, an indicator i 1, 6, l  indicating indices of the M l  bases included in the selected basis subset; and based on the condition not being satisfied, transmitting, to the BS, an indicator i 1, 5  indicating indices of the N′ bases included in the selected intermediate basis set.

CROSS-REFERENCE TO RELATED APPLICATION(S) AND CLAIM OF PRIORITY

This application is a continuation of U.S. patent application Ser. No.16/829,716, filed on Mar. 25, 2020, which claims priority to: U.S.Provisional Patent Application No. 62/832,053 filed on Apr. 10, 2019;U.S. Provisional Patent Application No. 62/834,597, filed on Apr. 16,2019; U.S. Provisional Patent Application No. 62/840,556 filed on Apr.30, 2019; U.S. Provisional Patent Application No. 62/845,514, filed onMay 9, 2019; U.S. Provisional Patent Application No. 62/846,956 filed onMay 13, 2019; and U.S. Provisional Patent Application No. 62/928,690,filed on Oct. 31, 2019. The content of the above-identified patentdocuments is incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates generally to wireless communicationsystems and more specifically to channel state information (CSI)reporting in wireless communication systems.

BACKGROUND

Understanding and correctly estimating the channel between a userequipment (UE) and a base station (BS) (e.g., gNode B (gNB)) isimportant for efficient and effective wireless communication. In orderto correctly estimate the DL channel conditions, the gNB may transmit areference signal, e.g., CSI-RS, to the UE for DL channel measurement,and the UE may report (e.g., feedback) information about channelmeasurement, e.g., CSI, to the gNB. With this DL channel measurement,the gNB is able to select appropriate communication parameters toefficiently and effectively perform wireless data communication with theUE.

SUMMARY

Embodiments of the present disclosure provide methods and apparatuses toenable CSI reporting in a wireless communication system.

In one embodiment, a UE is provided. The UE includes a processorconfigured to: in response to a condition being satisfied, select, froma full basis set, a basis subset comprising M_(l) bases for each layer lof a plurality of v layers; and in response to the condition not beingsatisfied, select, from the full basis set, an intermediate basis set(IntS) comprising N′ bases that are common among the plurality of vlayers, and select, from the selected intermediate basis set, the basissubset comprising M_(l) bases for each layer l of the plurality of vlayers. The UE further includes a transceiver operably connected to theprocessor. The transceiver is configured to: transmit, to a base station(BS), for each layer l of the plurality of v layers, an indicatori_(1, 6, 1) indicating indices of the M_(l) bases included in theselected basis subset; and based on the condition not being satisfied,transmit, to the BS, an indicator i_(1, 5) indicating indices of the N′bases included in the selected intermediate basis set (IntS), whereinthe full basis set comprises N₃ bases, and wherein N₃, N′, and M_(l) arepositive integers; M_(l)<N₃ when the condition is satisfied andM_(l)<N′<N₃ when the condition is not satisfied; l∈{1, 6. . . , v}; andv≥1 is a rank value.

In another embodiment, a BS is provided. The BS includes a transceiverconfigured to receive, from a user equipment (UE), (i) for each layer lof a plurality of v layers, an indicator i_(1, 6, 1) indicating indicesof M_(l) bases included in a basis subset and (ii) based on a conditionnot being satisfied, an indicator i_(1, 5) indicating indices of N′bases included in an intermediate basis set (IntS). The BS furtherincludes a processor operably connected to the transceiver. Theprocessor is configured to: when the condition is satisfied, use theindicator i_(1, 6, 1) to determine, from a full basis set, M_(l) basesincluded in the basis subset for each layer l of the plurality of vlayers; and when the condition is not satisfied, use the indicatori_(1, 5) to determine, from the full basis set, N′ bases included in theintermediate basis set (IntS) that are common among the plurality of vlayers, and use the received indicator i_(1, 6, 1) to determine, fromthe intermediate basis set, M_(l) bases included in the basis subset foreach layer l of the plurality of v layers, wherein the full basis setcomprises N₃ bases, and wherein N₃, N′, and M_(l) are positive integers;M_(l)<N₃ when the condition is satisfied and M_(l)<N′<N₃ when thecondition is not satisfied; l∈{1, 6. . . , v}; and v≥1 is a rank value.

In yet another embodiment, a method for operating a UE is provided. Themethod comprises: in response to a condition being satisfied, selecting,from a full basis set, a basis subset comprising M_(l) bases for eachlayer l of a plurality of v layers; in response to the condition notbeing satisfied, selecting, from the full basis set, an intermediatebasis set (IntS) comprising N′ bases that are common among the pluralityof v layers, and selecting, from the selected intermediate basis set,the basis subset comprising M_(l) bases for each layer l of theplurality of v layers; transmitting, to a base station (BS), for eachlayer l of the plurality of v layers, an indicator i_(1, 6, 1)indicating indices of the M_(l) bases included in the selected basissubset; and based on the condition not being satisfied, transmitting, tothe BS, an indicator i_(1, 5) indicating indices of the N′ basesincluded in the selected intermediate basis set (IntS); wherein the fullbasis set comprises N₃ bases, wherein N₃, N′, and M_(l) are positiveintegers; M_(l) <N₃ when the condition is satisfied and M_(l) <N′ <N₃when the condition is not satisfied; l∈{1, 6. . . , v}; and v≥1 is arank value.

Other technical features may be readily apparent to one skilled in theart from the following figures, descriptions, and claims.

Before undertaking the DETAILED DESCRIPTION below, it may beadvantageous to set forth definitions of certain words and phrases usedthroughout this patent document. The term “couple” and its derivativesrefer to any direct or indirect communication between two or moreelements, whether or not those elements are in physical contact with oneanother. The terms “transmit,” “receive,” and “communicate,” as well asderivatives thereof, encompass both direct and indirect communication.The terms “include” and “comprise,” as well as derivatives thereof, meaninclusion without limitation. The term “or” is inclusive, meaningand/or. The phrase “associated with,” as well as derivatives thereof,means to include, be included within, interconnect with, contain, becontained within, connect to or with, couple to or with, be communicablewith, cooperate with, interleave, juxtapose, be proximate to, be boundto or with, have, have a property of, have a relationship to or with, orthe like. The term “controller” means any device, system or part thereofthat controls at least one operation. Such a controller may beimplemented in hardware or a combination of hardware and software and/orfirmware. The functionality associated with any particular controllermay be centralized or distributed, whether locally or remotely. Thephrase “at least one of,” when used with a list of items, means thatdifferent combinations of one or more of the listed items may be used,and only one item in the list may be needed. For example, “at least oneof: A, B, and C” includes any of the following combinations: A, B, C, Aand B, A and C, B and C, and A and B and C.

Moreover, various functions described below can be implemented orsupported by one or more computer programs, each of which is formed fromcomputer readable program code and embodied in a computer readablemedium. The terms “application” and “program” refer to one or morecomputer programs, software components, sets of instructions,procedures, functions, objects, classes, instances, related data, or aportion thereof adapted for implementation in a suitable computerreadable program code. The phrase “computer readable program code”includes any type of computer code, including source code, object code,and executable code. The phrase “computer readable medium” includes anytype of medium capable of being accessed by a computer, such as readonly memory (ROM), random access memory (RAM), a hard disk drive, acompact disc (CD), a digital video disc (DVD), or any other type ofmemory. A “non-transitory” computer readable medium excludes wired,wireless, optical, or other communication links that transporttransitory electrical or other signals. A non-transitory computerreadable medium includes media where data can be permanently stored andmedia where data can be stored and later overwritten, such as arewritable optical disc or an erasable memory device.

Definitions for other certain words and phrases are provided throughoutthis patent document. Those of ordinary skill in the art shouldunderstand that in many if not most instances, such definitions apply toprior as well as future uses of such defined words and phrases.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present disclosure and itsadvantages, reference is now made to the following description taken inconjunction with the accompanying drawings, in which like referencenumerals represent like parts:

FIG. 1 illustrates an example wireless network according to embodimentsof the present disclosure;

FIG. 2 illustrates an example gNB according to embodiments of thepresent disclosure;

FIG. 3 illustrates an example UE according to embodiments of the presentdisclosure;

FIG. 4A illustrates a high-level diagram of an orthogonal frequencydivision multiple access transmit path according to embodiments of thepresent disclosure;

FIG. 4B illustrates a high-level diagram of an orthogonal frequencydivision multiple access receive path according to embodiments of thepresent disclosure;

FIG. 5 illustrates a transmitter block diagram for a PDSCH in a subframeaccording to embodiments of the present disclosure;

FIG. 6 illustrates a receiver block diagram for a PDSCH in a subframeaccording to embodiments of the present disclosure;

FIG. 7 illustrates a transmitter block diagram for a PUSCH in a subframeaccording to embodiments of the present disclosure;

FIG. 8 illustrates a receiver block diagram for a PUSCH in a subframeaccording to embodiments of the present disclosure;

FIG. 9 illustrates an example network configuration according toembodiments of the present disclosure;

FIG. 10 illustrates an example multiplexing of two slices according toembodiments of the present disclosure;

FIG. 11 illustrates an example antenna blocks according to embodimentsof the present disclosure;

FIG. 12 illustrates an example antenna port layout according toembodiments of the present disclosure;

FIG. 13 illustrates an example 3D grid of oversampled DFT beamsaccording to embodiments of the present disclosure;

FIG. 14 illustrates an example window-based intermediate basis setaccording to embodiments of the present disclosure;

FIG. 15 illustrates a flow chart of a method for transmitting an ULtransmission including CSI reporting, as may be performed by a UEaccording to embodiments of the present disclosure; and

FIG. 16 illustrates a flow chart of another method for receiving an ULtransmission including CSI reporting, as may be performed by a BS,according to embodiments of the present disclosure.

DETAILED DESCRIPTION

FIGS. 1 through FIG. 16, discussed below, and the various embodimentsused to describe the principles of the present disclosure in this patentdocument are by way of illustration only and should not be construed inany way to limit the scope of the disclosure. Those skilled in the artwill understand that the principles of the present disclosure may beimplemented in any suitably arranged system or device.

The following documents and standards descriptions are herebyincorporated by reference into the present disclosure as if fully setforth herein: 3GPP TS 36.211 v16.0.0, “E-UTRA, Physical channels andmodulation;” 3GPP TS 36.212 v16.0.0, “E-UTRA, Multiplexing and Channelcoding;” 3GPP TS 36.213 v16.0.0, “E-UTRA, Physical Layer Procedures;”3GPP TS 36.321 v16.0.0, “E-UTRA, Medium Access Control (MAC) protocolspecification;” 3GPP TS 36.331 v16.0.0, “E-UTRA, Radio Resource Control(RRC) protocol specification;” 3GPP TR 22.891 v14.2.0; 3GPP TS 38.211v16.0.0, “E-UTRA, NR, Physical channels and modulation;” 3GPP TS 38.213v16.0.0, “E-UTRA, NR, Physical Layer Procedures for control;” 3GPP TS38.214 v16.0.0, “E-UTRA, NR, Physical layer procedures for data;” and3GPP TS 38.212 v16.0.0, “E-UTRA, NR, Multiplexing and channel coding.”

Aspects, features, and advantages of the disclosure are readily apparentfrom the following detailed description, simply by illustrating a numberof particular embodiments and implementations, including the best modecontemplated for carrying out the disclosure. The disclosure is alsocapable of other and different embodiments, and its several details canbe modified in various obvious respects, all without departing from thespirit and scope of the disclosure. Accordingly, the drawings anddescription are to be regarded as illustrative in nature, and not asrestrictive. The disclosure is illustrated by way of example, and not byway of limitation, in the figures of the accompanying drawings.

In the following, for brevity, both FDD and TDD are considered as theduplex method for both DL and UL signaling.

Although exemplary descriptions and embodiments to follow assumeorthogonal frequency division multiplexing (OFDM) or orthogonalfrequency division multiple access (OFDMA), the present disclosure canbe extended to other OFDM-based transmission waveforms or multipleaccess schemes such as filtered OFDM (F-OFDM).

To meet the demand for wireless data traffic having increased sincedeployment of 4G communication systems, efforts have been made todevelop an improved 5G or pre-5G communication system. Therefore, the 5Gor pre-5G communication system is also called a “beyond 4G network” or a“post LTE system.”

The 5G communication system is considered to be implemented in higherfrequency (mmWave) bands, e.g., 60 GHz bands, so as to accomplish higherdata rates. To decrease propagation loss of the radio waves and increasethe transmission coverage, the beamforming, massive multiple-inputmultiple-output (MIMO), full dimensional MIMO (FD-MIMO), array antenna,an analog beam forming, large scale antenna techniques and the like arediscussed in 5G communication systems.

In addition, in 5G communication systems, development for system networkimprovement is under way based on advanced small cells, cloud radioaccess networks (RANs), ultra-dense networks, device-to-device (D2D)communication, wireless backhaul communication, moving network,cooperative communication, coordinated multi-points (CoMP) transmissionand reception, interference mitigation and cancellation and the like.

In the 5G system, hybrid frequency shift keying and quadrature amplitudemodulation (FQAM) and sliding window superposition coding (SWSC) as anadaptive modulation and coding (AMC) technique, and filter bank multicarrier (FBMC), non-orthogonal multiple access (NOMA), and sparse codemultiple access (SCMA) as an advanced access technology have beendeveloped.

FIGS. 1-4B below describe various embodiments implemented in wirelesscommunications systems and with the use of orthogonal frequency divisionmultiplexing (OFDM) or orthogonal frequency division multiple access(OFDMA) communication techniques. The descriptions of FIGS. 1-3 are notmeant to imply physical or architectural limitations to the manner inwhich different embodiments may be implemented. Different embodiments ofthe present disclosure may be implemented in any suitably-arrangedcommunications system. The present disclosure covers several componentswhich can be used in conjunction or in combination with one another, orcan operate as standalone schemes.

FIG. 1 illustrates an example wireless network according to embodimentsof the present disclosure. The embodiment of the wireless network shownin FIG. 1 is for illustration only. Other embodiments of the wirelessnetwork 100 could be used without departing from the scope of thisdisclosure.

As shown in FIG. 1, the wireless network includes a gNB 101, a gNB 102,and a gNB 103. The gNB 101 communicates with the gNB 102 and the gNB103. The gNB 101 also communicates with at least one network 130, suchas the Internet, a proprietary Internet Protocol (IP) network, or otherdata network.

The gNB 102 provides wireless broadband access to the network 130 for afirst plurality of user equipments (UEs) within a coverage area 120 ofthe gNB 102. The first plurality of UEs includes a UE 111, which may belocated in a small business; a UE 112, which may be located in anenterprise (E); a UE 113, which may be located in a WiFi hotspot (HS); aUE 114, which may be located in a first residence (R); a UE 115, whichmay be located in a second residence (R); and a UE 116, which may be amobile device (M), such as a cell phone, a wireless laptop, a wirelessPDA, or the like. The gNB 103 provides wireless broadband access to thenetwork 130 for a second plurality of UEs within a coverage area 125 ofthe gNB 103. The second plurality of UEs includes the UE 115 and the UE116. In some embodiments, one or more of the gNBs 101-103 maycommunicate with each other and with the UEs 111-116 using 5G, LTE,LTE-A, WiMAX, WiFi, or other wireless communication techniques.

Depending on the network type, the term “base station” or “BS” can referto any component (or collection of components) configured to providewireless access to a network, such as transmit point (TP),transmit-receive point (TRP), an enhanced base station (eNodeB or eNB),a 5G base station (gNB), a macrocell, a femtocell, a WiFi access point(AP), or other wirelessly enabled devices. Base stations may providewireless access in accordance with one or more wireless communicationprotocols, e.g., 5G 3GPP new radio interface/access (NR), long termevolution (LTE), LTE advanced (LTE-A), high speed packet access (HSPA),Wi-Fi 802.11a/b/g/n/ac, etc. For the sake of convenience, the terms “BS”and “TRP” are used interchangeably in this patent document to refer tonetwork infrastructure components that provide wireless access to remoteterminals. Also, depending on the network type, the term “userequipment” or “UE” can refer to any component such as “mobile station,”“subscriber station,” “remote terminal,” “wireless terminal,” “receivepoint,” or “user device.” For the sake of convenience, the terms “userequipment” and “UE” are used in this patent document to refer to remotewireless equipment that wirelessly accesses a BS, whether the UE is amobile device (such as a mobile telephone or smartphone) or is normallyconsidered a stationary device (such as a desktop computer or vendingmachine).

Dotted lines show the approximate extents of the coverage areas 120 and125, which are shown as approximately circular for the purposes ofillustration and explanation only. It should be clearly understood thatthe coverage areas associated with gNBs, such as the coverage areas 120and 125, may have other shapes, including irregular shapes, dependingupon the configuration of the gNBs and variations in the radioenvironment associated with natural and man-made obstructions. Asdescribed in more detail below, one or more of the UEs 111-116 includecircuitry, programing, or a combination thereof, to enable CSI reportingin a wireless communication system.

Although FIG. 1 illustrates one example of a wireless network, variouschanges may be made to FIG. 1. For example, the wireless network couldinclude any number of gNBs and any number of UEs in any suitablearrangement. Also, the gNB 101 could communicate directly with anynumber of UEs and provide those UEs with wireless broadband access tothe network 130. Similarly, each gNB 102-103 could communicate directlywith the network 130 and provide UEs with direct wireless broadbandaccess to the network 130. Further, the gNBs 101, 102, and/or 103 couldprovide access to other or additional external networks, such asexternal telephone networks or other types of data networks.

FIG. 2 illustrates an example gNB 102 according to embodiments of thepresent disclosure. The embodiment of the gNB 102 illustrated in FIG. 2is for illustration only, and the gNBs 101 and 103 of FIG. 1 could havethe same or similar configuration. However, gNBs come in a wide varietyof configurations, and FIG. 2 does not limit the scope of thisdisclosure to any particular implementation of a gNB.

As shown in FIG. 2, the gNB 102 includes multiple antennas 205 a-205 n,multiple RF transceivers 210 a-210 n, transmit (TX) processing circuitry215, and receive (RX) processing circuitry 220. The gNB 102 alsoincludes a controller/processor 225, a memory 230, and a backhaul ornetwork interface 235.

The RF transceivers 210 a-210 n receive, from the antennas 205 a-205 n,incoming RF signals, such as signals transmitted by UEs in the network100. The RF transceivers 210 a-210 n down-convert the incoming RFsignals to generate IF or baseband signals. The IF or baseband signalsare sent to the RX processing circuitry 220, which generates processedbaseband signals by filtering, decoding, and/or digitizing the basebandor IF signals. The RX processing circuitry 220 transmits the processedbaseband signals to the controller/processor 225 for further processing.

The TX processing circuitry 215 receives analog or digital data (such asvoice data, web data, e-mail, or interactive video game data) from thecontroller/processor 225. The TX processing circuitry 215 encodes,multiplexes, and/or digitizes the outgoing baseband data to generateprocessed baseband or IF signals. The RF transceivers 210 a-210 nreceive the outgoing processed baseband or IF signals from the TXprocessing circuitry 215 and up-converts the baseband or IF signals toRF signals that are transmitted via the antennas 205 a-205 n.

The controller/processor 225 can include one or more processors or otherprocessing devices that control the overall operation of the gNB 102.For example, the controller/processor 225 could control the reception offorward channel signals and the transmission of reverse channel signalsby the RF transceivers 210 a-210 n, the RX processing circuitry 220, andthe TX processing circuitry 215 in accordance with well-knownprinciples. The controller/processor 225 could support additionalfunctions as well, such as more advanced wireless communicationfunctions.

For instance, the controller/processor 225 could support beam forming ordirectional routing operations in which outgoing signals from multipleantennas 205 a-205 n are weighted differently to effectively steer theoutgoing signals in a desired direction. Any of a wide variety of otherfunctions could be supported in the gNB 102 by the controller/processor225.

The controller/processor 225 is also capable of executing programs andother processes resident in the memory 230, such as an OS. Thecontroller/processor 225 can move data into or out of the memory 230 asrequired by an executing process.

The controller/processor 225 is also coupled to the backhaul or networkinterface 235. The backhaul or network interface 235 allows the gNB 102to communicate with other devices or systems over a backhaul connectionor over a network. The interface 235 could support communications overany suitable wired or wireless connection(s). For example, when the gNB102 is implemented as part of a cellular communication system (such asone supporting 5G, LTE, or LTE-A), the interface 235 could allow the gNB102 to communicate with other gNBs over a wired or wireless backhaulconnection. When the gNB 102 is implemented as an access point, theinterface 235 could allow the gNB 102 to communicate over a wired orwireless local area network or over a wired or wireless connection to alarger network (such as the Internet). The interface 235 includes anysuitable structure supporting communications over a wired or wirelessconnection, such as an Ethernet or RF transceiver.

The memory 230 is coupled to the controller/processor 225. Part of thememory 230 could include a RAM, and another part of the memory 230 couldinclude a Flash memory or other ROM.

Although FIG. 2 illustrates one example of gNB 102, various changes maybe made to FIG. 2. For example, the gNB 102 could include any number ofeach component shown in FIG. 2. As a particular example, an access pointcould include a number of interfaces 235, and the controller/processor225 could support routing functions to route data between differentnetwork addresses. As another particular example, while shown asincluding a single instance of TX processing circuitry 215 and a singleinstance of RX processing circuitry 220, the gNB 102 could includemultiple instances of each (such as one per RF transceiver). Also,various components in FIG. 2 could be combined, further subdivided, oromitted and additional components could be added according to particularneeds.

FIG. 3 illustrates an example UE 116 according to embodiments of thepresent disclosure. The embodiment of the UE 116 illustrated in FIG. 3is for illustration only, and the UEs 111-115 of FIG. 1 could have thesame or similar configuration. However, UEs come in a wide variety ofconfigurations, and FIG. 3 does not limit the scope of this disclosureto any particular implementation of a UE.

As shown in FIG. 3, the UE 116 includes an antenna 305, a radiofrequency (RF) transceiver 310, TX processing circuitry 315, amicrophone 320, and receive (RX) processing circuitry 325. The UE 116also includes a speaker 330, a processor 340, an input/output (I/O)interface (IF) 345, a touchscreen 350, a display 355, and a memory 360.The memory 360 includes an operating system (OS) 361 and one or moreapplications 362.

The RF transceiver 310 receives, from the antenna 305, an incoming RFsignal transmitted by a gNB of the network 100. The RF transceiver 310down-converts the incoming RF signal to generate an intermediatefrequency (IF) or baseband signal. The IF or baseband signal is sent tothe RX processing circuitry 325, which generates a processed basebandsignal by filtering, decoding, and/or digitizing the baseband or IFsignal. The RX processing circuitry 325 transmits the processed basebandsignal to the speaker 330 (such as for voice data) or to the processor340 for further processing (such as for web browsing data).

The TX processing circuitry 315 receives analog or digital voice datafrom the microphone 320 or other outgoing baseband data (such as webdata, e-mail, or interactive video game data) from the processor 340.The TX processing circuitry 315 encodes, multiplexes, and/or digitizesthe outgoing baseband data to generate a processed baseband or IFsignal. The RF transceiver 310 receives the outgoing processed basebandor IF signal from the TX processing circuitry 315 and up-converts thebaseband or IF signal to an RF signal that is transmitted via theantenna 305.

The processor 340 can include one or more processors or other processingdevices and execute the OS 361 stored in the memory 360 in order tocontrol the overall operation of the UE 116. For example, the processor340 could control the reception of forward channel signals and thetransmission of reverse channel signals by the RF transceiver 310, theRX processing circuitry 325, and the TX processing circuitry 315 inaccordance with well-known principles. In some embodiments, theprocessor 340 includes at least one microprocessor or microcontroller.

The processor 340 is also capable of executing other processes andprograms resident in the memory 360, such as processes for CSI feedbackon uplink channel. The processor 340 can move data into or out of thememory 360 as required by an executing process. In some embodiments, theprocessor 340 is configured to execute the applications 362 based on theOS 361 or in response to signals received from gNBs or an operator. Theprocessor 340 is also coupled to the I/O interface 345, which providesthe UE 116 with the ability to connect to other devices, such as laptopcomputers and handheld computers. The I/O interface 345 is thecommunication path between these accessories and the processor 340.

The processor 340 is also coupled to the touchscreen 350 and the display355. The operator of the UE 116 can use the touchscreen 350 to enterdata into the UE 116. The display 355 may be a liquid crystal display,light emitting diode display, or other display capable of rendering textand/or at least limited graphics, such as from web sites.

The memory 360 is coupled to the processor 340. Part of the memory 360could include a random access memory (RAM), and another part of thememory 360 could include a Flash memory or other read-only memory (ROM).

Although FIG. 3 illustrates one example of UE 116, various changes maybe made to FIG. 3. For example, various components in FIG. 3 could becombined, further subdivided, or omitted and additional components couldbe added according to particular needs. As a particular example, theprocessor 340 could be divided into multiple processors, such as one ormore central processing units (CPUs) and one or more graphics processingunits (GPUs). Also, while FIG. 3 illustrates the UE 116 configured as amobile telephone or smartphone, UEs could be configured to operate asother types of mobile or stationary devices.

FIG. 4A is a high-level diagram of transmit path circuitry. For example,the transmit path circuitry may be used for an orthogonal frequencydivision multiple access (OFDMA) communication. FIG. 4B is a high-leveldiagram of receive path circuitry. For example, the receive pathcircuitry may be used for an orthogonal frequency division multipleaccess (OFDMA) communication. In FIGS. 4A and 4B, for downlinkcommunication, the transmit path circuitry may be implemented in a basestation (gNB) 102 or a relay station, and the receive path circuitry maybe implemented in a user equipment (e.g., user equipment 116 of FIG. 1).In other examples, for uplink communication, the receive path circuitry450 may be implemented in a base station (e.g., gNB 102 of FIG. 1) or arelay station, and the transmit path circuitry may be implemented in auser equipment (e.g., user equipment 116 of FIG. 1).

Transmit path circuitry comprises channel coding and modulation block405, serial-to-parallel (S-to-P) block 410, Size N Inverse Fast FourierTransform (IFFT) block 415, parallel-to-serial (P-to-S) block 420, addcyclic prefix block 425, and up-converter (UC) 430. Receive pathcircuitry 450 comprises down-converter (DC) 455, remove cyclic prefixblock 460, serial-to-parallel (S-to-P) block 465, Size N Fast FourierTransform (FFT) block 470, parallel-to-serial (P-to-S) block 475, andchannel decoding and demodulation block 480.

At least some of the components in FIGS. 4A 400 and 4B 450 may beimplemented in software, while other components may be implemented byconfigurable hardware or a mixture of software and configurablehardware. In particular, it is noted that the FFT blocks and the IFFTblocks described in this disclosure document may be implemented asconfigurable software algorithms, where the value of Size N may bemodified according to the implementation.

Furthermore, although this disclosure is directed to an embodiment thatimplements the Fast Fourier Transform and the Inverse Fast FourierTransform, this is by way of illustration only and may not be construedto limit the scope of the disclosure. It may be appreciated that in analternate embodiment of the present disclosure, the Fast FourierTransform functions and the Inverse Fast Fourier Transform functions mayeasily be replaced by discrete Fourier transform (DFT) functions andinverse discrete Fourier transform (IDFT) functions, respectively. Itmay be appreciated that for DFT and IDFT functions, the value of the Nvariable may be any integer number (i.e., 1, 4, 3, 4, etc.), while forFFT and IFFT functions, the value of the N variable may be any integernumber that is a power of two (i.e., 1, 2, 4, 8, 16, etc.).

In transmit path circuitry 400, channel coding and modulation block 405receives a set of information bits, applies coding (e.g., LDPC coding)and modulates (e.g., quadrature phase shift keying (QPSK) or quadratureamplitude modulation (QAM)) the input bits to produce a sequence offrequency-domain modulation symbols. Serial-to-parallel block 410converts (i.e., de-multiplexes) the serial modulated symbols to paralleldata to produce N parallel symbol streams where N is the IFFT/FFT sizeused in BS 102 and UE 116. Size N IFFT block 415 then performs an IFFToperation on the N parallel symbol streams to produce time-domain outputsignals. Parallel-to-serial block 420 converts (i.e., multiplexes) theparallel time-domain output symbols from Size N IFFT block 415 toproduce a serial time-domain signal. Add cyclic prefix block 425 theninserts a cyclic prefix to the time-domain signal. Finally, up-converter430 modulates (i.e., up-converts) the output of add cyclic prefix block425 to RF frequency for transmission via a wireless channel. The signalmay also be filtered at baseband before conversion to RF frequency.

The transmitted RF signal arrives at the UE 116 after passing throughthe wireless channel, and reverse operations to those at gNB 102 areperformed. Down-converter 455 down-converts the received signal tobaseband frequency, and remove cyclic prefix block 460 removes thecyclic prefix to produce the serial time-domain baseband signal.Serial-to-parallel block 465 converts the time-domain baseband signal toparallel time-domain signals. Size N FFT block 470 then performs an FFTalgorithm to produce N parallel frequency-domain signals.Parallel-to-serial block 475 converts the parallel frequency-domainsignals to a sequence of modulated data symbols. Channel decoding anddemodulation block 480 demodulates and then decodes the modulatedsymbols to recover the original input data stream.

Each of gNBs 101-103 may implement a transmit path that is analogous totransmitting in the downlink to user equipment 111-116 and may implementa receive path that is analogous to receiving in the uplink from userequipment 111-116. Similarly, each one of user equipment 111-116 mayimplement a transmit path corresponding to the architecture fortransmitting in the uplink to gNBs 101-103 and may implement a receivepath corresponding to the architecture for receiving in the downlinkfrom gNBs 101-103.

5G communication system use cases have been identified and described.Those use cases can be roughly categorized into three different groups.In one example, enhanced mobile broadband (eMBB) is determined to dowith high bits/sec requirement, with less stringent latency andreliability requirements. In another example, ultra-reliable and lowlatency (URLL) is determined with less stringent bits/sec requirement.In yet another example, massive machine type communication (mMTC) isdetermined that a number of devices can be as many as 100,000 to 1million per km2, but the reliability/throughput/latency requirementcould be less stringent. This scenario may also involve power efficiencyrequirement as well, in that the battery consumption may be minimized aspossible.

A communication system includes a downlink (DL) that conveys signalsfrom transmission points such as base stations (BS s) or NodeBs to userequipments (UEs) and an Uplink (UL) that conveys signals from UEs toreception points such as NodeBs. A UE, also commonly referred to as aterminal or a mobile station, may be fixed or mobile and may be acellular phone, a personal computer device, or an automated device. AneNodeB, which is generally a fixed station, may also be referred to asan access point or other equivalent terminology. For LTE systems, aNodeB is often referred as an eNodeB.

In a communication system, such as LTE system, DL signals can includedata signals conveying information content, control signals conveying DLcontrol information (DCI), and reference signals (RS) that are alsoknown as pilot signals. An eNodeB transmits data information through aphysical DL shared channel (PDSCH). An eNodeB transmits DCI through aphysical DL control channel (PDCCH) or an Enhanced PDCCH (EPDCCH).

An eNodeB transmits acknowledgement information in response to datatransport block (TB) transmission from a UE in a physical hybrid ARQindicator channel (PHICH). An eNodeB transmits one or more of multipletypes of RS including a UE-common RS (CRS), a channel state informationRS (CSI-RS), or a demodulation RS (DMRS). A CRS is transmitted over a DLsystem bandwidth (BW) and can be used by UEs to obtain a channelestimate to demodulate data or control information or to performmeasurements. To reduce CRS overhead, an eNodeB may transmit a CSI-RSwith a smaller density in the time and/or frequency domain than a CRS.DMRS can be transmitted only in the BW of a respective PDSCH or EPDCCHand a UE can use the DMRS to demodulate data or control information in aPDSCH or an EPDCCH, respectively. A transmission time interval for DLchannels is referred to as a subframe and can have, for example,duration of 1 millisecond.

DL signals also include transmission of a logical channel that carriessystem control information. A BCCH is mapped to either a transportchannel referred to as a broadcast channel (BCH) when the DL signalsconvey a master information block (MIB) or to a DL shared channel(DL-SCH) when the DL signals convey a System Information Block (SIB).Most system information is included in different SIB s that aretransmitted using DL-SCH. A presence of system information on a DL-SCHin a subframe can be indicated by a transmission of a correspondingPDCCH conveying a codeword with a cyclic redundancy check (CRC)scrambled with system information RNTI (SI-RNTI). Alternatively,scheduling information for a SIB transmission can be provided in anearlier SIB and scheduling information for the first SIB (SIB-1) can beprovided by the MIB.

DL resource allocation is performed in a unit of subframe and a group ofphysical resource blocks (PRB s). A transmission BW includes frequencyresource units referred to as resource blocks (RBs). Each RB includesN_(sc) ^(RB) sub-carriers, or resource elements (REs), such as 12 REs. Aunit of one RB over one subframe is referred to as a PRB. A UE can beallocated M_(PDSCH) RBs for a total of M_(sc) ^(PDSCH)=M_(PDSCH)·N_(sc)^(RB) REs for the PDSCH transmission BW.

UL signals can include data signals conveying data information, controlsignals conveying UL control information (UCI), and UL RS. UL RSincludes DMRS and Sounding RS (SRS). A UE transmits DMRS only in a BW ofa respective PUSCH or PUCCH. An eNodeB can use a DMRS to demodulate datasignals or UCI signals. A UE transmits SRS to provide an eNodeB with anUL CSI. A UE transmits data information or UCI through a respectivephysical UL shared channel (PUSCH) or a Physical UL control channel(PUCCH). If a UE needs to transmit data information and UCI in a same ULsubframe, the UE may multiplex both in a PUSCH. UCI includes HybridAutomatic Repeat request acknowledgement (HARQ-ACK) information,indicating correct (ACK) or incorrect (NACK) detection for a data TB ina PDSCH or absence of a PDCCH detection (DTX), scheduling request (SR)indicating whether a UE has data in the UE's buffer, rank indicator(RI), and channel state information (CSI) enabling an eNodeB to performlink adaptation for PDSCH transmissions to a UE. HARQ-ACK information isalso transmitted by a UE in response to a detection of a PDCCH/EPDCCHindicating a release of semi-persistently scheduled PDSCH.

An UL subframe includes two slots. Each slot includes N_(symb) ^(UL)symbols for transmitting data information, UCI, DMRS, or SRS. Afrequency resource unit of an UL system BW is a RB. A UE is allocatedN_(RB) RBs for a total of N_(RB)·N_(sc) ^(RB) REs for a transmission BW.For a PUCCH, N_(RB)=1. A last subframe symbol can be used to multiplexSRS transmissions from one or more UEs. A number of subframe symbolsthat are available for data/UCl/DMRS transmission isN_(symb)=2·(N_(symb) ^(UL)−1)−N_(SRS), where N_(SRS) if a last subframesymbol is used to transmit SRS and N_(SRS)=0 otherwise.

FIG. 5 illustrates a transmitter block diagram 500 for a PDSCH in asubframe according to embodiments of the present disclosure. Theembodiment of the transmitter block diagram 500 illustrated in FIG. 5 isfor illustration only. One or more of the components illustrated in FIG.5 can be implemented in specialized circuitry configured to perform thenoted functions or one or more of the components can be implemented byone or more processors executing instructions to perform the notedfunctions. FIG. 5 does not limit the scope of this disclosure to anyparticular implementation of the transmitter block diagram 500.

As shown in FIG. 5, information bits 510 are encoded by encoder 520,such as a turbo encoder, and modulated by modulator 530, for exampleusing quadrature phase shift keying (QPSK) modulation. A serial toparallel (S/P) converter 540 generates M modulation symbols that aresubsequently provided to a mapper 550 to be mapped to REs selected by atransmission BW selection unit 555 for an assigned PDSCH transmissionBW, unit 560 applies an Inverse fast Fourier transform (IFFT), theoutput is then serialized by a parallel to serial (P/S) converter 570 tocreate a time domain signal, filtering is applied by filter 580, and asignal transmitted 590. Additional functionalities, such as datascrambling, cyclic prefix insertion, time windowing, interleaving, andothers are well known in the art and are not shown for brevity.

FIG. 6 illustrates a receiver block diagram 600 for a PDSCH in asubframe according to embodiments of the present disclosure. Theembodiment of the diagram 600 illustrated in FIG. 6 is for illustrationonly. One or more of the components illustrated in

FIG. 6 can be implemented in specialized circuitry configured to performthe noted functions or one or more of the components can be implementedby one or more processors executing instructions to perform the notedfunctions. FIG. 6 does not limit the scope of this disclosure to anyparticular implementation of the diagram 600.

As shown in FIG. 6, a received signal 610 is filtered by filter 620, REs630 for an assigned reception BW are selected by BW selector 635, unit640 applies a fast Fourier transform (FFT), and an output is serializedby a parallel-to-serial converter 650. Subsequently, a demodulator 660coherently demodulates data symbols by applying a channel estimateobtained from a DMRS or a CRS (not shown), and a decoder 670, such as aturbo decoder, decodes the demodulated data to provide an estimate ofthe information data bits 680. Additional functionalities such astime-windowing, cyclic prefix removal, de-scrambling, channelestimation, and de-interleaving are not shown for brevity.

FIG. 7 illustrates a transmitter block diagram 700 for a PUSCH in asubframe according to embodiments of the present disclosure. Theembodiment of the block diagram 700 illustrated in FIG. 7 is forillustration only. One or more of the components illustrated in FIG. 5can be implemented in specialized circuitry configured to perform thenoted functions or one or more of the components can be implemented byone or more processors executing instructions to perform the notedfunctions. FIG. 7 does not limit the scope of this disclosure to anyparticular implementation of the block diagram 700.

As shown in FIG. 7, information data bits 710 are encoded by encoder720, such as a turbo encoder, and modulated by modulator 730. A discreteFourier transform (DFT) unit 740 applies a DFT on the modulated databits, REs 750 corresponding to an assigned PUSCH transmission BW areselected by transmission BW selection unit 755, unit 760 applies an IFFTand, after a cyclic prefix insertion (not shown), filtering is appliedby filter 770 and a signal transmitted 780.

FIG. 8 illustrates a receiver block diagram 800 for a PUSCH in asubframe according to embodiments of the present disclosure. Theembodiment of the block diagram 800 illustrated in FIG. 8 is forillustration only. One or more of the components illustrated in FIG. 8can be implemented in specialized circuitry configured to perform thenoted functions or one or more of the components can be implemented byone or more processors executing instructions to perform the notedfunctions. FIG. 8 does not limit the scope of this disclosure to anyparticular implementation of the block diagram 800.

As shown in FIG. 8, a received signal 810 is filtered by filter 820.Subsequently, after a cyclic prefix is removed (not shown), unit 830applies a FFT, REs 840 corresponding to an assigned PUSCH reception BWare selected by a reception BW selector 845, unit 850 applies an inverseDFT (IDFT), a demodulator 860 coherently demodulates data symbols byapplying a channel estimate obtained from a DMRS (not shown), a decoder870, such as a turbo decoder, decodes the demodulated data to provide anestimate of the information data bits 880.

In next generation cellular systems, various use cases are envisionedbeyond the capabilities of LTE system. Termed 5G or the fifth generationcellular system, a system capable of operating at sub-6GHz and above-6GHz (for example, in mmWave regime) becomes one of the requirements. In3GPP TR 22.891, 74 5G use cases have been identified and described;those use cases can be roughly categorized into three different groups.A first group is termed “enhanced mobile broadband (eMBB),” targeted tohigh data rate services with less stringent latency and reliabilityrequirements. A second group is termed “ultra-reliable and low latency(URLL)” targeted for applications with less stringent data raterequirements, but less tolerant to latency. A third group is termed“massive MTC (mMTC)” targeted for large number of low-power deviceconnections such as 1 million per km² with less stringent thereliability, data rate, and latency requirements.

FIG. 9 illustrates an example network configuration 900 according toembodiments of the present disclosure. The embodiment of the networkconfiguration 900 illustrated in FIG. 9 is for illustration only. FIG. 9does not limit the scope of this disclosure to any particularimplementation of the configuration 900.

In order for the 5G network to support such diverse services withdifferent quality of services (QoS), one scheme has been identified in3GPP specification, called network slicing.

As shown in FIG. 9, an operator's network 910 includes a number of radioaccess network(s) 920 (RAN(s)) that are associated with network devicessuch as gNBs 930 a and 930 b, small cell base stations (femto/pico gNBsor Wi-Fi access points) 935 a and 935 b. The network 910 can supportvarious services, each represented as a slice.

In the example, an URLL slice 940 a serves UEs requiring URLL servicessuch as cars 945 b, trucks 945 c, smart watches 945 a, and smart glasses945 d. Two mMTC slices 950 a and 950 b serve UEs requiring mMTC servicessuch as power meters 955 a, and temperature control box 955 b. One eMBBslice 960 a serves UEs requiring eMBB services such as cells phones 965a, laptops 965 b, and tablets 965 c. A device configured with two slicescan also be envisioned.

To utilize PHY resources efficiently and multiplex various slices (withdifferent resource allocation schemes, numerologies, and schedulingstrategies) in DL-SCH, a flexible and self-contained frame or subframedesign is utilized.

FIG. 10 illustrates an example multiplexing of two slices 1000 accordingto embodiments of the present disclosure. The embodiment of themultiplexing of two slices 1000 illustrated in FIG. 10 is forillustration only. One or more of the components illustrated in FIG. 5can be implemented in specialized circuitry configured to perform thenoted functions or one or more of the components can be implemented byone or more processors executing instructions to perform the notedfunctions. FIG. 10 does not limit the scope of this disclosure to anyparticular implementation of the multiplexing of two slices 1000.

Two exemplary instances of multiplexing two slices within a commonsubframe or frame are depicted in FIG. 10. In these exemplaryembodiments, a slice can be composed of one or two transmissioninstances where one transmission instance includes a control (CTRL)component (e.g., 1020 a, 1060 a, 1060 b, 1020 b, or 1060 c) and a datacomponent (e.g., 1030 a, 1070 a, 1070 b, 1030 b, or 1070c). Inembodiment 1010, the two slices are multiplexed in frequency domainwhereas in embodiment 1050, the two slices are multiplexed in timedomain.

The 3GPP NR specification supports up to 32 CSI-RS antenna ports whichenable a gNB to be equipped with a large number of antenna elements(such as 64 or 128). In this case, a plurality of antenna elements ismapped onto one CSI-RS port. For next generation cellular systems suchas 5G, the maximum number of CSI-RS ports can either remain the same orincrease.

FIG. 11 illustrates an example antenna blocks 1100 according toembodiments of the present disclosure. The embodiment of the antennablocks 1100 illustrated in FIG. 11 is for illustration only. FIG. 11does not limit the scope of this disclosure to any particularimplementation of the antenna blocks 1100.

For mmWave bands, although the number of antenna elements can be largerfor a given form factor, the number of CSI-RS ports which can correspondto the number of digitally precoded ports tends to be limited due tohardware constraints (such as the feasibility to install a large numberof ADCs/DACs at mmWave frequencies) as illustrated in FIG. 11. In thiscase, one CSI-RS port is mapped onto a large number of antenna elementswhich can be controlled by a bank of analog phase shifters. One CSI-RSport can then correspond to one sub-array which produces a narrow analogbeam through analog beamforming. This analog beam can be configured tosweep across a wider range of angles by varying the phase shifter bankacross symbols or subframes. The number of sub-arrays (equal to thenumber of RF chains) is the same as the number of CSI-RS portsN_(CSI-PORT). A digital beamforming unit performs a linear combinationacross N_(CSI-PORT) analog beams to further increase precoding gain.While analog beams are wideband (hence not frequency-selective), digitalprecoding can be varied across frequency sub-bands (SBs) or resourceblocks.

To enable digital precoding, efficient design of CSI-RS is a crucialfactor. For this reason, three types of CSI reporting mechanismcorresponding to three types of CSI-RS measurement behavior aresupported, for example, “CLASS A” CSI reporting which corresponds tonon-precoded CSI-RS, “CLASS B” reporting with K=1 CSI-RS resource whichcorresponds to UE-specific beamformed CSI-RS, and “CLASS B” reportingwith K>1 CSI-RS resources which corresponds to cell-specific beamformedCSI-RS.

For non-precoded (NP) CSI-RS, a cell-specific one-to-one mapping betweenCSI-RS port and TXRU is utilized. Different CSI-RS ports have the samewide beam width and direction and hence generally cell wide coverage.For beamformed CSI-RS, beamforming operation, either cell-specific orUE-specific, is applied on a non-zero-power (NZP) CSI-RS resource (e.g.,comprising multiple ports). At least at a given time/frequency, CSI-RSports have narrow beam widths and hence not cell wide coverage, and atleast from the gNB perspective. At least some CSI-RS port-resourcecombinations have different beam directions.

In scenarios where DL long-term channel statistics can be measuredthrough UL signals at a serving eNodeB, UE-specific BF CSI-RS can bereadily used. This is typically feasible when UL-DL duplex distance issufficiently small. When this condition does not hold, however, some UEfeedback is necessary for the eNodeB to obtain an estimate of DLlong-term channel statistics (or any of representation thereof). Tofacilitate such a procedure, a first BF CSI-RS transmitted withperiodicity T1 (ms) and a second NP CSI-RS transmitted with periodicityT2 (ms), where T1 T2. This approach is termed hybrid CSI-RS. Theimplementation of hybrid CSI-RS is largely dependent on the definitionof CSI process and NZP CSI-RS resource.

In the 3GPP LTE specification, MIMO has been identified as an essentialfeature in order to achieve high system throughput requirements and itwill continue to be the same in NR. One of the key components of a MIMOtransmission scheme is the accurate CSI acquisition at the eNB (or TRP).For MU-MIMO, in particular, the availability of accurate CSI isnecessary in order to guarantee high MU performance. For TDD systems,the CSI can be acquired using the SRS transmission relying on thechannel reciprocity. For FDD systems, on the other hand, the CSI can beacquired using the CSI-RS transmission from the eNB, and CSI acquisitionand feedback from the UE. In legacy FDD systems, the CSI feedbackframework is ‘implicit’ in the form of CQI/PMI/RI derived from acodebook assuming SU transmission from the eNB. Because of the inherentSU assumption while deriving CSI, this implicit CSI feedback isinadequate for MU transmission. Since future (e.g., NR) systems arelikely to be more MU-centric, this SU-MU CSI mismatch will be abottleneck in achieving high MU performance gains. Another issue withimplicit feedback is the scalability with larger number of antenna portsat the eNB. For large number of antenna ports, the codebook design forimplicit feedback is quite complicated, and the performance benefits inpractical deployment scenarios (for example, only a small percentagegain can be shown at the most).

In 5G or NR systems, the above-mentioned CSI reporting paradigm from LTEis also supported and referred to as Type I CSI reporting. In additionto Type I, a high-resolution CSI reporting, referred to as Type II CSIreporting, is also supported to provide more accurate CSI information togNB for use cases such as high-order MU-MIMO.

FIG. 12 illustrates an example antenna port layout 1200 according toembodiments of the present disclosure. The embodiment of the antennaport layout 1200 illustrated in FIG. 12 is for illustration only. FIG.12 does not limit the scope of this disclosure to any particularimplementation of the antenna port layout 1200.

As illustrated in FIG. 12, N₁ and N₂ are the number of antenna portswith the same polarization in the first and second dimensions,respectively. For 2D antenna port layouts, N₁>1, N₂>1, and for 1Dantenna port layouts N₁>1 and N₂=1. Therefore, for a dual-polarizedantenna port layout, the total number of antenna ports is 2N₁N₂.

As described in U.S. patent application Ser. No. 15/490,561, filed Apr.18, 2017 and entitled “Method and Apparatus for Explicit CSI Reportingin Advanced Wireless Communication Systems,” which is incorporatedherein by reference in its entirety, a UE is configured withhigh-resolution (e.g., Type II) CSI reporting in which the linearcombination based Type II CSI reporting framework is extended to includea frequency dimension in addition to the first and second antenna portdimensions.

FIG. 13 illustrates a 3D grid 1300 of the oversampled DFT beams (1stport dim., 2nd port dim., freq. dim.) in which

-   -   1st dimension is associated with the 1st port dimension,    -   2nd dimension is associated with the 2nd port dimension, and    -   3rd dimension is associated with the frequency dimension.        The basis sets for 1^(st) and 2^(nd) port domain representation        are oversampled DFT codebooks of length-N₁ and length-N₂,        respectively, and with oversampling factors O₁ and O₂,        respectively. Likewise, the basis set for frequency domain        representation (i.e., 3rd dimension) is an oversampled DFT        codebook of length-N₃ and with oversampling factor O₃. In one        example, O₁=O₂=O₃=4. In another example, the oversampling        factors O_(i) belongs to {2, 4, 8}. In yet another example, at        least one of O₁, O₂, and O₃ is higher layer configured (via RRC        signaling).

A UE is configured with higher layer parameter CodebookType set to‘TypeII-Compression’ or ‘TypeIII’ for an enhanced Type II CSI reportingin which the pre-coders for all SBs and for a given layer l=1, . . . ,v, where v is the associated RI value, is given by either

$\begin{matrix}{W^{l} = {{AC_{l}B^{H}} = {{\left\lbrack {a_{0}a_{1}\mspace{14mu}\ldots\mspace{14mu} a_{L - 1}} \right\rbrack\begin{bmatrix}c_{l,0,0} & c_{l,0,1} & \ldots & c_{l,0,{M - 1}} \\c_{l,1,0} & c_{l,1,1} & \ldots & c_{l,1,M - 1} \\\vdots & \vdots & \vdots & \vdots \\c_{l,{L - 1},0} & c_{l,{L - 1},1} & \ldots & c_{l,{L - 1},{M - 1}}\end{bmatrix}}{\quad{{\left\lbrack {b_{0}b_{1}\mspace{14mu}\ldots\mspace{14mu} b_{M - 1}} \right\rbrack^{H} = {{\sum\limits_{m = 0}^{M - 1}{\sum\limits_{i = 0}^{L - 1}{c_{l,i,m}\left( {a_{i}b_{m}^{H}} \right)}}} = {\sum\limits_{i = 0}^{L - 1}{\sum\limits_{m = 0}^{M - 1}{c_{l,i,m}\left( {a_{i}b_{m}^{H}} \right)}}}}},}}}}} & \left( {{Eq}.\mspace{14mu} 1} \right) \\{\mspace{79mu}{or}} & \; \\{W^{l} = {{\begin{Bmatrix}A & 0 \\0 & A\end{Bmatrix}\ C_{l}B^{H}} = {\begin{bmatrix}{a_{0}a_{1}\mspace{14mu}\ldots\mspace{14mu} a_{L - 1}} & 0 \\0 & {a_{0}a_{1}\mspace{14mu}\ldots\mspace{14mu} a_{L - 1}}\end{bmatrix}{\quad{\begin{bmatrix}c_{l,0,0} & c_{l,0,1} & \ldots & c_{l,0,{M - 1}} \\c_{l,1,0} & c_{l,1,1} & \ldots & c_{l,1,M - 1} \\\vdots & \vdots & \vdots & \vdots \\c_{l,{L - 1},0} & c_{l,{L - 1},1} & \ldots & c_{l,{L - 1},{M - 1}}\end{bmatrix}{\quad{{\left\lbrack {b_{0}b_{1}\mspace{14mu}\ldots\mspace{14mu} b_{M - 1}} \right\rbrack^{H} = \begin{bmatrix}{\sum\limits_{m = 0}^{M - 1}{\sum\limits_{i = 0}^{L - 1}{c_{l,i,m}\left( {a_{i}b_{m}^{H}} \right)}}} \\{\sum\limits_{m = 0}^{M - 1}{\sum\limits_{i = 0}^{L - 1}{c_{l,{i + L},m}\left( {a_{i}b_{m}^{H}} \right)}}}\end{bmatrix}},}}}}}}} & \left( {{Eq}.\mspace{14mu} 2} \right)\end{matrix}$

where

-   -   N₁ is a number of antenna ports in a first antenna port        dimension,    -   N₂ is a number of antenna ports in a second antenna port        dimension,    -   N₃ is a number of SBs or frequency domain (FD) units/components        for PMI reporting (that comprise the CSI reporting band), which        can be different (e.g., less than) from a number of SBs for CQI        reporting.    -   a_(i) is a 2N₁N₂×1 (Eq. 1) or N₁N₂×1 (Eq. 2) column vector,    -   b_(m) is a N₃×1 column vector,    -   c_(l, i, m) is a complex coefficient.

In a variation, when a subset K<2LM coefficients (where K is eitherfixed, configured by the gNB or reported by the UE), then thecoefficient c_(l, i, m) in precoder equations Eq. 1 or Eq. 2 is replacedwith v_(l, i, m)×c_(l, i, m), where

-   -   v_(l, i, m)=1 if the coefficient c_(l, i, m) is non-zero, hence        reported by the UE according to some embodiments of this        disclosure.    -   v_(l, i, m)=0 otherwise (i.e., c_(l, i, m) is zero, hence not        reported by the UE).        The indication whether v_(l, i, m)=1 or 0 is according to some        embodiments of this disclosure.

In a variation, the precoder equations Eq. 1 or Eq. 2 are respectivelygeneralized to

$\begin{matrix}{W^{l} = {\sum\limits_{i = 0}^{L - 1}{\sum\limits_{m = 0}^{M_{i} - 1}{c_{l,i,m}\left( {a_{i}b_{i,m}^{H}} \right)}}}} & \left( {{Eq}.\mspace{14mu} 3} \right) \\{and} & \; \\{{W^{l} = \begin{bmatrix}{\sum\limits_{i = 0}^{L - 1}{\sum\limits_{m = 0}^{M_{i} - 1}{c_{l,i,m}\left( {a_{i}b_{i,m}^{H}} \right)}}} \\{\sum\limits_{i = 0}^{L - 1}{\sum\limits_{m = 0}^{M_{i} - 1}{c_{l,{i + L},m}\left( {a_{i}b_{i,m}^{H}} \right)}}}\end{bmatrix}},} & \left( {{Eq}.\mspace{14mu} 4} \right)\end{matrix}$

where for a given i, the number of basis vectors is M_(i) and thecorresponding basis vectors are {b_(i,m)}. Note that M_(i) is the numberof coefficients reported by the UE for a given i, where M_(i)<M (where{M_(i)} or ΣE M_(i) is either fixed, configured by the gNB or reportedby the UE).

The columns of W^(l) are normalized to norm one. For rank R or R layers(v=R), the pre-coding matrix is given by

$W^{(R)} = {{\frac{1}{\sqrt{R}}\begin{bmatrix}W^{1} & W^{2} & \ldots & W^{R}\end{bmatrix}}.}$

Eq. 2 is assumed in the rest of the disclosure. The embodiments of thedisclosure, however, are general and are also applicable to Eq. 1, Eq. 3and Eq. 4.

L≤2N₁N₂ and K≤N₃. If L=2N₁N₂, then A is an identity matrix, and hencenot reported. Likewise, if K=N₃, then B is an identity matrix, and hencenot reported. Assuming L<2N₁N₂, in an example, to report columns of A,the oversampled DFT codebook is used. For instance, a_(i)=v_(l,m), wherethe quantity v_(l,m) is given by:

$u_{m} = \left\{ {{\begin{matrix}\begin{bmatrix}1 & e^{j\;\frac{2\pi\; m}{O_{2}N_{2}}} & \ldots & e^{j\;\frac{2\pi\;{m{({N_{2} - 1})}}}{O_{2}N_{2}}}\end{bmatrix} & {N_{2} > 1} \\1 & {N_{2} = 1}\end{matrix}.v_{l,m}} = \begin{bmatrix}u_{m} & {e^{j\;\frac{2\pi\; l}{O_{1}N_{1}}}u_{m}} & \ldots & {e^{j\;\frac{2\pi\;{l{({N_{1} - 1})}}}{O_{1}N_{1}}}u_{m}}\end{bmatrix}^{T}} \right.$

Similarly, assuming K<N₃, in an example, to report columns of B, theoversampled

DFT codebook is used. For instance, b_(k)=w_(k), where the quantityw_(k) is given by:

$w_{k} = {\begin{bmatrix}1 & e^{j\;\frac{2\pi\; k}{O_{3}N_{3}}} & \ldots & e^{j\;\frac{2\pi\;{k{({N_{3} - 1})}}}{O_{3}N_{3}}}\end{bmatrix}.}$

In another example, discrete cosine transform DCT basis is used toconstruct/report basis B for the 3^(rd) dimension. The m-th column ofthe DCT compression matrix is simply given by

$\left\lbrack w_{f} \right\rbrack_{nm} = \left\{ {\begin{matrix}{\frac{1}{\sqrt{K}},{n = 0}} \\{{\sqrt{\frac{2}{K}}\cos\frac{{\pi\left( {{2m} + 1} \right)}n}{2K}},{n = 1},\ldots\mspace{14mu},{K - 1}}\end{matrix},,{{{and}K} = N_{3}},{{{and}\mspace{14mu} m} = 0},\ldots\mspace{14mu},{N_{3} - 1.}} \right.$

Since DCT is applied to real valued coefficients, the DCT is applied tothe real and imaginary components (of the channel or channeleigenvectors) separately. Alternatively, the DCT is applied to themagnitude and phase components (of the channel or channel eigenvectors)separately. The use of DFT or DCT basis is for illustration purposeonly. The disclosure is applicable to any other basis vectors toconstruct/report A and B.

Also, in an alternative, for reciprocity-based Type II CSI reporting, aUE is configured with higher layer parameter CodebookType set to‘TypeII-PortSelection-Compression’ or ‘TypeIII-PortSelection’ for anenhanced Type II CSI reporting with port selection in which thepre-coders for all SBs and for a given layer l=1, . . . , v, where v isthe associated RI value, is given by W^(l)=AC_(l)B^(H), where N₁, N₂,N₃, and c_(l,i,k) are defined as above except that the matrix Acomprises port selection vectors. For instance, the L antenna ports perpolarization or column vectors of A are selected by the index q₁, where

$q_{1} \in \left\{ {0,1,\ldots\mspace{14mu},{\left\lceil \frac{F_{{CSI} - {RS}}}{2d} \right\rceil - 1}} \right\}$

(this requires

$\left. {\left\lceil {\log_{2}\left\lceil \frac{P_{{CSI} - {RS}}}{2d} \right\rceil} \right\rceil\mspace{14mu}{bits}} \right),$

and the value of d is configured with the higher layer parameterPortSelectionSamplingSize, where d∈{1, 2, 3, 4} and

${d \leq {\min\left( {\frac{F_{{CSI} - {RS}}}{2},L} \right)}}.$

To report columns of A, the port selection vectors are used,

For instance, a_(i)=v_(m), where the quantity v_(m), is aP_(CSI-RS)/2-element column vector containing a value of 1 in element(mmodP_(CSI-RS)/2) and zeros elsewhere (where the first element iselement 0).

On a high level, a precoder W^(l) can be described as follows.

W^(l)=AC_(l)B^(H)=W₁{tilde over (W)}₂W_(f) ^(H),   (5)

where A=W₁ corresponds to the W₁ in Type II CSI codebook, i.e.,

$W_{1} = \begin{bmatrix}A & 0 \\0 & A\end{bmatrix}$

and B=W_(f). The C={tilde over (W)}₂ matrix consists of all the requiredlinear combination coefficients (e.g., amplitude and phase or real orimaginary). Each reported coefficient(c_(l, i, m)=p_(l, i, m)ϕ_(l, i, m)) in {tilde over (W)}₂ is quantizedas amplitude coefficient (p_(l, i, m))and phase coefficient(ϕ_(l, i, m)).

In one example, the spatial domain (SD) beams or basis vectors arereported in a layer-common manner, i.e., a set of L SD basis vectors arereported by the UE that are common for all layers l=0, 1, . . . , v−1,where v is the RI value reported by the UE. The set of L SD basisvectors are reported via part 2 of a two-part UCI comprising UCI part 1and UCI part 2. For example, this reporting is via a SD basis subsetindicator

${i_{SD} \in \left\{ {0,1,\ldots\mspace{14mu},{\begin{pmatrix}{N_{1}N_{2}} \\L\end{pmatrix} - 1}} \right\}},$

similar to L beam reporting.

In one example, i_(SD) is a component of the first PMI i₁.

In one example, the frequency domain (SD) beams or basis vectors arereported in a layer-specific manner, i.e., a set of M_(l) FD basisvectors are reported by the UE independently for each layer l=0, 1, . .. , v−1. For each layer l∈{0, 1, . . . , v−1}, the set of M_(l) FD basisvectors are reported via part 2 of a two-part UCI comprising UCI part 1and UCI part 2. For example, this reporting is via a FD basis subsetindicator i_(FD)=[i_(FD, 0) i_(FD, 1). . . i_(FD, v−1)], where i_(FD, l)is a FD basis subset indicator for layer l. In one example, i_(FD) is acomponent of the first PMI i₁.

In one example, the set of M_(l) FD basis vectors are reported from anorthogonal DFT codebook comprising N₃ DFT vectors

${w_{k} = \begin{bmatrix}1 & e^{j\;\frac{2\pi\; k}{N_{3}}} & \ldots & e^{j\;\frac{2\pi\;{k{({N_{3} - 1})}}}{N_{3}}}\end{bmatrix}},$

where k=0, 1, . . . , N₃−1. In one example, N₃=R×N₃where R is higherlayer configured from {1, 2}, and N_(SB) is number of SBs for configuredfor CQI reporting. In another example, N₃ is the smallest integer suchthat N₃≥R×N₃and N₃ is a multiple of 2 or 3 or 5.

In one example,

$M_{l} = {\left\lceil {p_{l} \times \frac{N_{3}}{R}} \right\rceil.}$

In another example, M_(l)=[p_(l)×N_(SBp)]. Here p_(l) is a fraction, forexample,

$p_{l} \in {\left\{ {\frac{1}{4},\frac{1}{2}} \right\}\mspace{14mu}{or}\mspace{14mu} p_{l}} \in {\left\{ {\frac{1}{8},\frac{1}{4},\frac{1}{2}} \right\}.}$

Several embodiments about the reporting details of the FD basis vectorsare proposed.

In embodiment 0, for each layer l∈{0, 1, . . . , v−1}, the set of M_(l)FD basis vectors are reported by the UE according to at least one of thefollowing alternatives.

In one alternative Alt 0-0: the FD basis subset selection indicatori_(FD, l) is a

$\left\lceil {\log_{2}\begin{pmatrix}N_{3} \\M_{l}\end{pmatrix}} \right\rceil\text{-bit}$

indicator, where

$i_{{FD},l} \in {\left\{ {0,1,\ldots\mspace{14mu},{\begin{pmatrix}N_{3} \\M_{l}\end{pmatrix} - 1}} \right\}.}$

In one alternative Alt 0-1: the FD basis subset selection indicatori_(FD,i) is a

$\left\lceil {\log_{2}\begin{pmatrix}{N_{3} - 1} \\{M_{l} - 1}\end{pmatrix}} \right\rceil\text{-bit}$

indicator, where

$i_{{FD},l} \in {\left\{ {0,1,\ldots\mspace{14mu},{\begin{pmatrix}{N_{3} - 1} \\{M_{l} - 1}\end{pmatrix} - 1}} \right\}.}$

In this alternative, one of the

FD basis vectors is always fixed, and hence not reported by the UE. Inone example, this fixed FD basis vector is FD basis vector with index=0.

In one alternative Alt 0-2: the FD basis subset selection indicatori_(FD, l) is a size-N₃ bitmap, where i_(FD,1)=b₀b₁b_(N) ₃ , and the setof M_(l) FD basis vectors are indicated by reporting M_(l) of these bitsb_(i)'s to one and the rest to zero. Alternatively, the set of M_(l) FDbasis vectors are indicated by reporting M_(l) of these bits b_(i)'s tozero and the rest to one.

In embodiment 1, a two-step FD basis subset selection method is used.The first step uses an intermediate FD basis set comprising N′₃ basisvectors (where N′₃≤N₃). The value N′₃ is either reported by the UE(e.g., via part 1 of a two-part UCI) or fixed or higher-layerconfigured. The intermediate FD basis set is a common pool of FD basisvectors for all layers, and is reported via part 2 of a two-part UCI.The starting index) of the intermediate FD basis set is indicated via a┌log₂ N₃┐-bit indicator. The indices of the FD basis vectors in thisintermediate set is given by mod(M_(initial)+n, N₃), n=0, 1, . . . ,N′₃−1. In one example, N′₃=N′. The notation N′₃ and N′ are usedinterchangeably in this disclosure.

In the second step, for each layer l∈{0, 1, . . . , v−1} or l∈{1, . . ., v}, the set of M_(l) FD basis vectors are reported by the UE from theintermediate FD basis set according to at least one of the followingalternatives.

In one alternative Alt 1-0: the FD basis subset selection indicatori_(FD, l) is a

$\left\lceil {\log_{2}\begin{pmatrix}N_{3}^{\prime} \\M_{l}\end{pmatrix}} \right\rceil\text{-bit}$

indicator, where

$i_{{FD},l} \in {\left\{ {0,1,\ldots\mspace{14mu},{\begin{pmatrix}N_{3}^{\prime} \\M_{l}\end{pmatrix} - 1}} \right\}.}$

In one alternative Alt 1-1: the FD basis subset selection indicatori_(FD, l) is a

$\left\lceil {\log_{2}\begin{pmatrix}N_{3}^{\prime} \\{M_{l} - 1}\end{pmatrix}} \right\rceil\mspace{14mu}{or}\mspace{14mu}\left\lceil {\log_{2}\begin{pmatrix}{N_{3}^{\prime} - 1} \\{M_{l} - 1}\end{pmatrix}} \right\rceil\mspace{14mu}\text{-bit}$

indicator, where

$i_{{FD},l} \in {\left\{ {0,1,\ldots\mspace{14mu},{\begin{pmatrix}N_{3}^{\prime} \\{M_{l} - 1}\end{pmatrix} - {1\mspace{14mu}{or}\mspace{14mu}\begin{pmatrix}{N_{3}^{\prime} - 1} \\{M_{l} - 1}\end{pmatrix}} - 1}} \right\}.}$

In this alternative, one of the FD basis vectors is always fixed, andhence not reported by the UE. In one example, this fixed FD basis vectoris FD basis vector with index=0.

In one alternative Alt 1-2: the FD basis subset selection indicatori_(FD, l) is a size-N′₃ bitmap, where i_(FD, l)=b₀b₁. . . b_(N′) ₃ , andthe set of M_(l) FD basis vectors are indicated by reporting M_(l) ofthese bits b_(i)'s to one and the rest to zero. Alternatively, the setof M_(l) FD basis vectors are indicated by reporting M_(l) of these bitsb_(i)'s to zero and the rest to one.

In embodiment 1A, which is a variation of embodiment 1, the startingindex (M_(initial)) of the intermediate FD basis set is fixed, hence notreported by the UE. At least one of the following alternatives is used.

In one alternative Alt 1A-0: M_(initial)=0 indicating the FD component0.

In one alternative Alt 1A-1:

$M_{initial} = {N_{3} - \left\lceil \frac{N_{3}^{\prime}}{2} \right\rceil + {1.}}$

In one alternative Alt 1A-2:

${M_{initial} = {N_{3} - \left\lceil \frac{N_{3}^{\prime}}{2} \right\rceil + \Delta + 1}},$

where Δ is either fixed, e.g., Δ=1, or determined based on otherparameters such as N′₃.

In one alternative Alt 1A-3:

${M_{initial} = {N_{3} - \left\lceil \frac{N_{3}^{\prime}}{2} \right\rceil + \Delta}},$

where Δ is either fixed, e.g., Δ=1, or determined based on otherparameters such as N′₃.

In one alternative Alt 1A-4:

$M_{initial} = {N_{3} - \left\lfloor \frac{N_{3}^{\prime}}{2} \right\rfloor + 1.}$

In one alternative Alt 1A-5:

${M_{initial} = {N_{3} - \left\lfloor \frac{N_{3}^{\prime}}{2} \right\rfloor + \Delta + 1}},$

where Δ is either fixed, e.g., Δ=1, or determined based on otherparameters such as N′₃.

In one alternative Alt 1A-6:

${M_{initial} = {N_{3} - \left\lfloor \frac{N_{3}^{\prime}}{2} \right\rfloor + \Delta}},$

where Δ is either fixed, e.g., Δ=1, or determined based on otherparameters such as N′₃.

In embodiment 1B, which is a variation of embodiment 1, the startingindex (M_(initial)) of the intermediate FD basis set is higher-layerconfigured, hence not reported by the UE. At least one of the followingalternatives is used.

In one alternative Alt 1B-0: M_(initial) is higher-layer configured.

In one alternative Alt 1B-1:

${M_{initial} = {N_{3} - \left\lceil \frac{N_{3}^{\prime}}{2} \right\rceil + \Delta + 1}},$

where Δ is higher-layer configured.

In one alternative Alt 1B-2:

${M_{initial} = {N_{3} - \left\lfloor \frac{N_{3}^{\prime}}{2} \right\rfloor + \Delta + 1}},$

where Δ is higher-layer configured.

In one alternative Alt 1B-3:

${M_{initial} = {N_{3} - \left\lceil \frac{N_{3}^{\prime}}{2} \right\rceil + \Delta}},$

where Δ is higher-layer configured.

In one alternative Alt 1B-4:

${M_{initial} = {N_{3} - \left\lfloor \frac{N_{3}^{\prime}}{2} \right\rfloor + \Delta}},$

where Δ is higher-layer configured.

At least one of the following examples is used as the set of candidatevalues for Δ.

In one example, Δ∈{−1, 1} or {−2, 2}

In one example, Δ∈{−1, 0} or {−2, 0}

In one example, Δ∈{0, 1} or {0, 2}

In one example, Δ∈{−1, 0, 1}

In one example, Δ∈{−2, 0, 2}

In one example, Δ∈{−2, 1, 0, 1}

In one example, Δ∈{−1, 0, 1, 2}

In one example, Δ∈{−2, 1, 0, 1, 2}

In Embodiment 1C, which is a variation of embodiment 1, the startingindex (M_(initiai)) of the intermediate FD basis set is reported by theUE. At least one of the following alternatives is used.

In one alternative Alt 1C-0: M_(initial) is reported via a ┌log₂ N₃┐-bitindicator.

In one alternative Alt 1C-1:

${M_{initial} = {N_{3} - \left\lceil \frac{N_{3}^{\prime}}{2} \right\rceil + \Delta + 1}},$

where Δ is reported by the UE via a ┌log₂ B┐-bit indicator.

In one alternative Alt 1C-2:

${M_{initial} = {N_{3} - \left\lfloor \frac{N_{3}^{\prime}}{2} \right\rfloor + \Delta + 1}},$

where Δ is reported by the UE via a ┌log₂ B┐-bit indicator.

In one alternative Alt 1C-3:

${M_{initial} = {N_{3} - \left\lceil \frac{N_{3}^{\prime}}{2} \right\rceil + \Delta}},$

where Δ is reported by the UE via a ┌log₂ B┐-bit indicator.

In one alternative Alt 1C-4:

${M_{initial} = {N_{3} - \left\lfloor \frac{N_{3}^{\prime}}{2} \right\rfloor + \Delta}},$

where Δ is reported by the UE via a ┌log₂ B┐-bit indicator.

B is the number of candidate values for Δ. At least one of the followingis used as the set of candidate values for Δ.

-   -   B=2, hence a ┌log2┐-bit or 1-bit indicator is reported by the        UE.        -   Ex: Δ∈{−1, 1} or {−2, 2}        -   Ex: Δ∈{−2, 0}        -   Ex: Δ∈{0, 1} or {0, 2}    -   B=3, hence a ┌log ₂ 3┐-bit or 2-bit indicator is reported by the        UE.        -   Ex: Δ∈{−1, 0, 1}        -   Ex: Δ∈{−2, 0, 2}    -   B=4, hence a ┌log ₂ 4┐-bit or 2-bit indicator is reported by the        UE.        -   Ex: Δ∈{−2, −1, 0, 1}        -   Ex: Δ∈{−1, 0, 1, 2}    -   B=5. hence a ┌log₂5┐-bit or 3-bit indicator is reported by the        UE.        -   Ex: Δ∈{−2, −1, 0, 1, 2}

In embodiment 2, a two-step FD basis subset selection method is used.The first step uses an intermediate FD basis set comprising M basisvectors (where N′₃≤N₃). The value N′₃ is either reported by the UE(e.g., via part 1 of a two-part UCI or fixed or higher-layer configured.The intermediate FD basis set is a common pool of FD basis vectors forall layers, and is reported via part 2 of a two-part UCI. Theintermediate FD basis set is selected from multiple higher-layerconfigured intermediate sets.

In the second step, for each layer l∈{0, 1, . . . , v−1}, the set ofM_(l) FD basis vectors are reported by the UE from the selectedintermediate FD basis set according to at least one of the alternativesAlt 1-0, 1-1, and 1-2.

In embodiment 3, for each layer l∈{0, 1, . . . , v−1}, the set of M_(l)FD basis vectors are reported by the UE, where the starting index(M_(l,initial)) of the FD basis set is indicated via a ┌log ₂ N₃┐-bitindicator. The indices of the FD basis vectors is given bymod(M_(l,initial)+n, N₃), n=0, 1, . . . , M_(l)−1.

In embodiment 4, an intermediate FD basis set comprising M basis vectorsis higher layer configured, where N′₃ is fixed, hence not reported. Theintermediate FD basis set is common for all RI values, and for alllayers (hence, RI-common and layer-common). For each layer l∈ {0, 1, . .. , v−1}, the set of M_(l) FD basis vectors are reported by the UE fromthe intermediate FD basis set according to at least one of the followingalternatives.

In one alternative Alt 4-0: the FD basis subset selection indicatori_(FD, l) , is a

$\left\lceil {\log_{2}\begin{pmatrix}N_{3}^{\prime} \\M_{l}\end{pmatrix}} \right\rceil\text{-bit}$

indicator, where

$i_{F,D,l} \in {\left\{ {0,1,\ldots\mspace{14mu},{\begin{pmatrix}N_{3}^{\prime} \\M_{l}\end{pmatrix} - 1}} \right\}.}$

In one alternative Alt 4-1: the FD basis subset selection indicatori_(FD, l) is a

$\left\lceil {\log_{2}\begin{pmatrix}N_{3}^{\prime} \\{M_{l} - 1}\end{pmatrix}} \right\rceil\text{-bit}$

indicator, where

$i_{F,D,l} \in {\left\{ {0,1,\ldots\mspace{14mu},{\begin{pmatrix}N_{3}^{\prime} \\{M_{l} - 1}\end{pmatrix} - 1}} \right\}.}$

In this alternative, one of the FD basis vectors is always fixed, andhence not reported by the UE. In one example, this fixed FD basis vectoris FD basis vector with index=0.

In one alternative Alt 4-2: the FD basis subset selection indicatori_(FD, l) is a size-N′₃ bitmap, where i_(FD, l)=b₀b₁. . . b_(N′) ₃ , andthe set of M_(l) FD basis vectors are indicated by reporting M_(l) ofthese bits b_(i)'s to one and the rest to zero. Alternatively, the setof M_(l) FD basis vectors are indicated by reporting M_(l) of these bitsb_(i)'s to zero and the rest to one.

In embodiment 4A, which is a variation of embodiment 4, an intermediateFD basis set of size N′₃ is higher layer configured for each rank or RIvalue, and for a given RI value, the intermediate FD basis set is commonfor all layers (hence, RI-specific and layer-common). For each layerl∈{0, 1, . . . , v−1}, the set of M_(l) FD basis vectors are reported bythe UE from the respective intermediate FD basis set according to atleast one of the alternatives Alt 4-0, 4-1, and 4-2.

In embodiment 4B, which is a variation of embodiment 4, an intermediateFD basis set of size N′₃ is higher layer configured for each layervalue, and for a given layer value, the intermediate FD basis set iscommon for all ranks or RI values (hence, RI-common and layer-specific).For each layer l∈{0, 1, . . . , v−1}, the set of M_(l) FD basis vectorsare reported by the UE from the respective intermediate FD basis setaccording to at least one of the alternatives Alt 4-0, 4-1, and 4-2.

In embodiment 4C, which is a variation of embodiment 4, an intermediateFD basis set of size N′₃ is higher layer configured for each layervalue, and for each RI or rank value, (hence, RI-specific andlayer-specific). For each layer l∈{0,1, . . . , v−1}, the set of M_(l)FD basis vectors are reported by the UE from the respective intermediateFD basis set according to at least one of the alternatives Alt 4-0, 4-1,and 4-2.

In embodiment 5, a two-step FD basis subset selection method is used.The first step uses an intermediate FD basis set comprising N′₃ basisvectors (where N′₃≤N₃). The value N′₃ is either reported by the UE(e.g., via part 1 of a two-part UCI or fixed or higher-layer configured.The intermediate FD basis set is a common pool of FD basis vectors forall layers, and is reported via part 2 of a two-part UCI. In oneexample, the FD basis vectors in this intermediate set is the union ofFD basis vectors for all layers, and they are reported by the UE from anorthogonal DFT codebook comprising N₃ DFT vectors according to at leastone of the following alternatives.

In one alternative Alt 5-0: The intermediate FD basis set indicatori_(FD,interm) is a

$\left\lceil {\log_{2}\begin{pmatrix}N_{3} \\N_{3}^{\prime}\end{pmatrix}} \right\rceil{bit}$

indicator, where

$i_{{FD},{interm}} \in {\left\{ {0,1,\ldots\mspace{14mu},{\begin{pmatrix}N_{3} \\N_{3}^{\prime}\end{pmatrix} - 1}} \right\}.}$

In one alternative Alt 5-1: The intermediate FD basis set indicatori_(FD,interm) is a

$\left\lceil {\log_{2}\begin{pmatrix}{N_{3} - 1} \\{N_{3}^{\prime} - 1}\end{pmatrix}} \right\rceil\text{-bit}$

indicator, where

$i_{{FD},{interm}} \in {\left\{ {0,1,\ldots\mspace{14mu},{\begin{pmatrix}{N_{3} - 1} \\{N_{3}^{\prime} - 1}\end{pmatrix} - 1}} \right\}.}$

In this alternative, one of the FD basis vectors is always fixed, andhence not reported by the UE. In one example, this fixed FD basis vectoris FD basis vector with index=0.

In one alternative Alt 5-2: The intermediate FD basis set indicatori_(FD,interm) is a size-N₃ bitmap, where i_(FD,interm)=b₀b₁ . . . b_(N)₃ , and the intermediate set of N₃′ FD basis vectors are indicated byreporting N₃′ of these bits b_(i)'s to one and the rest to zero.Alternatively, the set of N₃′ FD basis vectors are indicated byreporting N₃′ of these bits b_(i)'s to zero and the rest to one.

In the second step, for each layer l∈{0, 1, . . . , v−1}, the set ofM_(l) FD basis vectors are reported by the UE from the intermediate FDbasis set according to at least one of the alternatives Alt 1-0, 1-1,and 1-2.

In embodiment 6, a UE is configured to report the FD basis vectorseither (A) without using any FD intermediate basis set or equivalentlyN′₃=N₃ (e.g., according to embodiment 0) or (B) using an FD intermediatebasis set (e.g., according to embodiment 1-5) based on a condition. Atleast one of the following alternatives is used for the condition.

In one alternative Alt 6-0: (A) is used when N₃≤x, and (B) is used whenN_(SB)>x, where x is a threshold.

In one alternative Alt 6-1: (A) is used when N₃<x, and (B) is used whenN₃≥x, where x is a threshold.

In one alternative Alt 6-2: (A) is used when N_(SB)≤x, and (B) is usedwhen N_(SB)>x, where x is a threshold.

In one alternative Alt 6-3: (A) is used when N_(SB)<x, and (B) is usedwhen N_(SB)>x, where x is a threshold.

The threshold x is either fixed, or configured, or reported by the UE.In one example, when x is fixed, then x=19 for Alt 6-0 and 6-1, and x=10or 13 for Alt 6-2 and 6-3. Note that when (A) is used, there is no needfor any intermediate basis set configuration/reporting.

In embodiment 6A, a UE is configured to report the FD basis vectorseither (A) without using any FD intermediate basis set or equivalently M=N₃ (e.g., according to embodiment 0) or (B) using an FD intermediatebasis set (e.g., according to embodiment 1-5) based on a condition onthe higher layer configured value R. In one alternative, (A) is usedwhen R=1, and (B) is used when R=2. In another alternative,

$N_{3}^{\prime} = {\frac{N_{3}}{R}\mspace{14mu}{or}\mspace{14mu}{\left\lceil \frac{N_{3}}{R} \right\rceil.}}$

In another alternative,

$N_{3}^{\prime} = {\left\lceil \frac{N_{3}}{2} \right\rceil.}$

In embodiment 6AA, a UE is configured to report the FD basis vectorseither (A) without using any FD intermediate basis set or equivalentlyN′₃=N₃ (e.g., according to embodiment 0) or (B) using an FD intermediatebasis set (e.g., according to embodiment 1-5) based on a condition onthe higher layer configured value R and another condition on N₃ orN_(SB). At least one of the following alternatives is used.

In one alternative Alt 6AA-0: (A) is used when N₃≤x and R=1, and (B) isused otherwise, where x is a threshold.

In one alternative Alt 6AA-1: (A) is used when N₃<x and R=1, and (B) isused otherwise, where x is a threshold.

In one alternative Alt 6AA-2: (A) is used when N_(SB)≤x and R=1, and (B)is used when N_(SB)>x, where x is a threshold.

In one alternative Alt 6AA-3: (A) is used when N_(SB)<x and R=1, and (B)is used when N_(SB)≥x, where x is a threshold.

In one alternative Alt 6AA-4: (A) is used when N₃≤x or R=1, and (B) isused otherwise, where x is a threshold.

In one alternative Alt 6AA-5: (A) is used when N₃<X or R=1, and (B) isused otherwise, where x is a threshold.

In one alternative Alt 6AA-6: (A) is used when N_(SB)≤x or R=1, and (B)is used when N_(SB)>x, where x is a threshold.

In one alternative Alt 6AA-7: (A) is used when N_(SB)<x or R=1, and (B)is used when N_(SB)≥x, where x is a threshold.

In embodiment 6B, a UE is configured to report the FD basis vectorseither (A) without using any FD intermediate basis set or equivalentlyN′₃=N₃ (e.g., according to embodiment 0) or (B) using an FD intermediatebasis set (e.g., according to embodiment 1-5) based on explicit higherlayer signaling.

In embodiment 6C, a UE is configured to report the FD basis vectorseither (A) without using any FD intermediate basis set or equivalentlyN′₃=N₃ (e.g., according to embodiment 0) or (B) using an FD intermediatebasis set (e.g., according to embodiment 1-5) based on UE capabilitysignaling. That is, the UE reports in its capability signaling whetherit supports (A), (B), or both. Or, the UE reports in its capabilitysignaling whether it supports (A), or both (A) and (B). When the UEsupports both (A) and (B), then one of (A) and (B) is configured to theUE via higher layer signaling.

In embodiment 6D, a UE is configured to report the FD basis vectorseither (A) without using any FD intermediate basis set or equivalentlyN′=N₃ (e.g., according to embodiment 0) or (B) using an FD intermediatebasis set (e.g., according to embodiment 1-5) based on the rank or RIvalue. In one example, the UE reports the FD basis vectors according to(A) when RI<3 (i.e., RI∈{1, 2}), and the UE reports the FD basis vectorsaccording to (B) when RI>2 (e.g., RI∈ {3, 4}). In another example, theUE reports the FD basis vectors according to (A) when RI<2 (i.e. RI=1),and the UE reports the FD basis vectors according to (B) when RI>1(i.e., RI≥2 or RI∈ {2, 3, 4}).

In embodiment 6E, a UE is configured to report the FD basis vectorseither (A) using an FD intermediate basis set according to embodiment Xor (B) using an FD intermediate basis set according to embodiment Y,where X≠Y, based on a condition. At least one of the followingalternatives is used for the condition.

In one alternative Alt 6E-0: (A) is used when N₃≤x, and (B) is used whenN₃>x, where x is a threshold.

In one alternative Alt 6E-1: (A) is used when N₃<x, and (B) is used whenN₃≥x, where x is a threshold.

In one alternative Alt 6E-2: (A) is used when N_(SB)≤x, and (B) is usedwhen N_(SB)>x, where x is a threshold.

In one alternative Alt 6E-3: (A) is used when N_(SB)<x, and (B) is usedwhen N_(SB)≥x, where x is a threshold.

The threshold x is either fixed, or configured, or reported by the UE.In one example, when x is fixed, then x=19 for Alt 6-0 and 6-1, and x=10or 13 for Alt 6-2 and 6-3. Note that when (A) is used, there is no needfor any intermediate basis set configuration/reporting. At least one ofthe examples (Ex) in Table 1 is used for the value (X, Y). In oneexample, only one value for (X, Y) is supported, e.g., 6E-16 for (X, Y)=(5,1). In another example, more than one values for (X, Y) aresupported, and one of the supported values is configured, e.g., viahigher layer signaling.

TABLE 1 Example for the value (X, Y). Ex X Y 6E-0 1 2 6E-1 1 3 6E-2 1 46E-3 1 5 6E-4 2 1 6E-5 2 3 6E-6 2 4 6E-7 2 5 6E-8 3 1 6E-9 3 2 6E-10 3 46E-11 3 5 6E-12 4 1 6E-13 4 2 6E-14 4 3 6E-15 4 5 6E-16 5 1 6E-17 5 26E-18 5 3 6E-19 5 4

In embodiment 6EE, a UE is configured to report the FD basis vectorseither (A) using an FD intermediate basis set according to embodiment Xor (B) using an FD intermediate basis set according to embodiment Y,where X≠Y, based on a condition on the higher layer configured value R.In one alternative, (A) is used when R=1, and (B) is used when R=2. Inanother alternative,

$N_{3}^{\prime} = {\frac{N_{3}}{R}\mspace{14mu}{or}\mspace{20mu}{\left\lceil \frac{N_{3}}{R} \right\rceil.}}$

In another alternative,

$N_{3}^{\prime} = {\left\lceil \frac{N_{3}}{2} \right\rceil.}$

At least one of the examples (Ex) in Table 1 is used for the value (X,Y). In one example, only one value for (X, Y) is supported, e.g., 6E-16for (X, Y)=(5,1). In another example, more than one values for (X, Y)are supported, and one of the supported values is configured, e.g., viahigher layer signaling.

In embodiment 6EEE, a UE is configured to report the FD basis vectorseither (A) using an FD intermediate basis set according to embodiment Xor (B) using an FD intermediate basis set according to embodiment Y,where X≠Y, based on a condition on the higher layer configured value Rand another condition on N₃ or N_(SB). At least one of the followingalternatives is used.

In one alternative Alt 6EEE-0: (A) is used when N₃≤x and R=1, and (B) isused otherwise, where x is a threshold.

In one alternative Alt 6EEE-1: (A) is used when N₃<X and R=1, and (B) isused otherwise, where x is a threshold.

In one alternative Alt 6EEE-2: (A) is used when N_(SB)≤x and R=1, and(B) is used when N_(SB)>x, where x is a threshold.

In one alternative Alt 6EEE-3: (A) is used when N_(SB)<X and R=1, and(B) is used when N₃>x, where x is a threshold.

In one alternative Alt 6EEE-4: (A) is used when N₃≤x or R=1, and (B) isused otherwise, where x is a threshold.

In one alternative Alt 6EEE-5: (A) is used when N₃<X or R=1, and (B) isused otherwise, where x is a threshold.

In one alternative Alt 6EEE-6: (A) is used when N_(SB)<x or R=1, and (B)is used when N_(SB)>x, where x is a threshold.

In one alternative Alt 6EEE-7: (A) is used when N_(SB)<X or R=1, and (B)is used when N_(SB)≥x, where x is a threshold.

At least one of the examples (Ex) in Table 1 is used for the value (X,Y). In one example, only one value for (X, Y) is supported, e.g., 6E-16for (X, Y)=(5,1). In another example, more than one values for (X, Y)are supported, and one of the supported values is configured, e.g., viahigher layer signaling.

In embodiment 6F, a UE is configured to report the FD basis vectorseither (A) using an FD intermediate basis set according to embodiment Xor (B) using an FD intermediate basis set according to embodiment Y,where X≠Y, based on explicit higher layer signaling. At least one of theexamples (Ex) in Table 1 is used for the value (X, Y). In one example,only one value for (X, Y) is supported, e.g., 6E-16 for (X, Y)=(5,1). Inanother example, more than one values for (X, Y) are supported, and oneof the supported values is configured, e.g., via higher layer signaling.

In embodiment 6G, a UE is configured to report the FD basis vectorseither (A) using an FD intermediate basis set according to embodiment Xor (B) using an FD intermediate basis set according to embodiment Y,where X≠Y, based on UE capability signaling. That is, the UE reports inits capability signaling whether it supports (A), (B), or both. Or, theUE reports in its capability signaling whether it supports (A), or both(A) and (B). When the UE supports both (A) and (B), then one of (A) and(B) is configured to the UE via higher layer signaling. At least one ofthe examples (Ex) in Table 1 is used for the value (X, Y). In oneexample, only one value for (X, Y) is supported, e.g., 6E-16 for (X,Y)=(5,1). In another example, more than one values for (X, Y) aresupported, and one of the supported values is configured, e.g., viahigher layer signaling.

In embodiment 6H, a UE is configured to report the FD basis vectorseither (A) using an FD intermediate basis set according to embodiment Xor (B) using an FD intermediate basis set according to embodiment Y,where X≠Y, based on the rank or RI value. In one example, the UE reportsthe FD basis vectors according to (A) when RI<3 (i.e., RI∈{1,2}), andthe UE reports the FD basis vectors according to (B) when RI>2 (e.g.,RI∈{3,4}). In another example, the UE reports the FD basis vectorsaccording to (A) when RI<2 (i.e. RI=1), and the UE reports the FD basisvectors according to (B) when RI>1 (i.e., RI≥2 or RI∈{2,3,4}). At leastone of the examples (Ex) in Table 1 is used for the value (X, Y). In oneexample, only one value for (X, Y) is supported, e.g., 6E-16 for (X,Y)=(5,1). In another example, more than one values for (X, Y) aresupported, and one of the supported values is configured, e.g., viahigher layer signaling.

In embodiment 7, the value N′₃ to determine the size of the FDintermediate basis set is determined according to at least one of thefollowing alternatives.

In one alternative

$N_{3}^{\prime} = \left\lceil {y \times \frac{N_{3}}{R}} \right\rceil$

is fixed.

In one alternative Alt 7-1: N′₃=┌y×N₃┐ is fixed.

In one alternative Alt 7-2: N′₃ 32 ┌y×N_(SB)┐ is fixed.

In one alternative Alt 7-3: N′₃=┌y×R×N_(SB)┐ is fixed.

In one alternative Alt 7-4:

$N_{3}^{\prime} = \left\lceil \frac{N_{3}}{R} \right\rceil$

is fixed.

In one alternative Alt 7-5: N′₃=N_(SB) is fixed.

In one alternative Alt 7-6: N′₃ is higher-layer configured.

In one alternative Alt 7-7: N′₃ is reported by the UE (e.g., via part 1of the two-part UCI).

In one alternative Alt 7-8: N′₃ is signaled via L1/L2 DL controlsignaling such as MAC CE or UL related DCI (together with CSI request).In one example, N′₃ is signaled from a set of candidate values. Inanother example, the candidate values of N′₃ are incorporated into thetrigger state definition.

In one alternative Alt 7-9: N′₃=M is fixed, where

$M = \left\lceil {p \times \frac{N_{3}}{R}} \right\rceil$

is number of FD units comprising columns of coefficient matrix C_(l),and p is higher layer configured, for example, from

$\left\{ {\frac{1}{4},\frac{1}{2}} \right\}.$

y is either fixed (e.g., to ¾), or configured, or reported by the UE.

In one alternative Alt 7-0-0, which is a sub-alternative of Alt 7-0,

$N_{3}^{\prime} = \left\lceil {y \times \frac{N_{3}}{R}} \right\rceil$

and y is determined according to at least one of the following examples.

In one example Ex 7-0-0-0: y is fixed. In one example, y=¾. In anotherexample, y=p+a, where a id fixed, e.g., a=¼. In another example, y=a×p,where a is fixed, e.g., a=2. In another example, y=p+a for rank 1-2 andy=v₀+a for rank 3-4, where a is fixed, e.g., a=¼. In another example,y=a×p for rank 1-2 and y=a×v₀ for rank 3-4, where a is fixed, e.g., a=2.Here, p is higher-layer configured to determine number of FD components

$M = \left\lceil {p \times \frac{N_{3}}{R}} \right\rceil$

for rank 1-2, and v₀ is higher-layer configured to determine number ofFD components

$M_{0} = \left\lceil {v_{0} \times \frac{N_{3}}{R}} \right\rceil$

for rank 3-4. In one example, p belongs to

$\left\{ {\frac{1}{4},\frac{1}{2}} \right\}$

and v₀ belongs to

$\left\{ {\frac{1}{4},\frac{1}{8}} \right\}.$

In one example Ex 7-0-0-1: y is higher-layer configured.

In one example Ex 7-0-0-1A, y is configured independently (separately)using a separate parameter which takes values from {y₁, y₂}. At leastone of the following is used.

-   -   {y₁, y₂} is independent of p value, e.g.,

$\left\{ {y_{1},y_{2}} \right\} = {\left\{ {\frac{2}{3},\frac{3}{4}} \right\}\mspace{14mu}{or}\mspace{14mu}\left\{ {\frac{5}{8},\frac{3}{4}} \right\}\mspace{14mu}{or}\mspace{14mu}\left\{ {\frac{1}{2},\frac{3}{4}} \right\}\mspace{14mu}{or}\mspace{14mu}\left\{ {1,\frac{3}{4}} \right\}}$

{y₁, y₂} depends on p value, e.g., if

${p = \frac{1}{4}},{\left\{ {y_{1},y_{2}} \right\} = \left\{ {\frac{1}{2},\frac{3}{4}} \right\}}$

and if

${p = \frac{1}{2}},{\left\{ {y_{1},y_{2}} \right\} = {\left\{ {\frac{2}{3},\frac{3}{4}} \right\}\mspace{14mu}{or}\mspace{14mu}{\left\{ {\frac{5}{8},\frac{3}{4}} \right\}.}}}$

In one example Ex 7-0-0-1B, y is configured implicitly (i.e., noseparate higher layer parameter is used) via a higher-layer parameter.At least one of the following is used.

-   -   y is configured implicitly via higher layer parameter p. At        least one of the following is used.        -   y=p+a, where a is fixed, e.g., a=¼        -   y=a×p, where a is fixed, e.g., a=2    -   y is configured implicitly via higher layer parameter (p, v₀).        At least one of the following is used.        -   y=p+a for rank 1-2 and y=v₀ for rank 3-4, where a is fixed,            e.g., a=¼        -   y=a×p for rank 1-2 and y=a×v₀ for rank 3-4, where a is            fixed, e.g., a=2

In one example Ex 7-0-0-1C, y is configured jointly with at least onehigher-layer parameter. At least one of the following is used.

-   -   y is configured jointly with higher layer parameter p

$\left( {p,y} \right) = {\left\{ {\left( {\frac{1}{4},\frac{1}{2}} \right),\left( {\frac{1}{2},\frac{3}{4}} \right)} \right\}.}$

y is configured jointly with higher layer parameter (p, v₀). At leastone of the following is used.

$\mspace{79mu}{\left( {p,v_{0},y} \right) = {{\left\{ {\left( {\frac{1}{4},\frac{1}{4},\frac{1}{2}} \right),\left( {\frac{1}{2},\frac{1}{4},\frac{3}{4}} \right)} \right\}.\mspace{79mu}\left( {p,v_{0},y} \right)} = {{\left\{ {\left( {\frac{1}{4},\frac{1}{8},\frac{1}{2}} \right),\left( {\frac{1}{4},\frac{1}{4},\frac{1}{2}} \right),\left( {\frac{1}{2},\frac{1}{4},\frac{3}{4}} \right)} \right\}.\mspace{79mu}\left( {p,v_{0},y} \right)} = {{\left\{ {\left( {\frac{1}{4},\frac{1}{8},\frac{1}{2}} \right),\left( {\frac{1}{2},\frac{1}{4},\frac{3}{4}} \right)} \right\}.\left( {p,v_{0},y} \right)} = \left\{ {\left( {\frac{1}{4},\frac{1}{8},\frac{1}{2}} \right),\left( {\frac{1}{4},\frac{1}{4},\frac{1}{2}} \right),\left( {\frac{1}{2},\frac{1}{4},\frac{3}{4}} \right),\left( {\frac{1}{2},\frac{1}{8},\frac{3}{4}} \right)} \right\}}}}}$

In one example Ex 7-0-0-2: y is reported in UCI part 1

In one example Ex 7-0-0-2A: a 1-bit indication is used to indicate oneof the two supported values {y₁, y₂}. At least one of the following isused.

-   -   The two supported values are fixed. At least one of the        following is used.        -   {y₁, y₂} is independent of p value, e.g.,

$\left\{ {y_{1},y_{2}} \right\} = {\left\{ {\frac{2}{3},\frac{3}{4}} \right\}\mspace{14mu}{or}\mspace{14mu}\left\{ {\frac{5}{8},\frac{3}{4}} \right\}\mspace{14mu}{or}\mspace{14mu}\left\{ {\frac{1}{2},\frac{3}{4}} \right\}}$

-   -   {y₁, y₂} depends on p value, e.g., if

${p = \frac{1}{4}},{\left\{ {y_{1},y_{2}} \right\} = \left\{ {\frac{1}{2},\frac{3}{4}} \right\}}$

and if

${p = \frac{1}{2}},{\left\{ {y_{1},y_{2}} \right\} = {\left\{ {\frac{2}{3},\frac{3}{4}} \right\}\mspace{14mu}{or}\mspace{14mu}{\left\{ {\frac{5}{8},\frac{3}{4}} \right\}.}}}$

-   -   The two supported values are higher-layer configured, e.g., from

$\left\{ {\frac{1}{2},\frac{5}{8},\frac{2}{3},\frac{3}{4},1} \right\}.$

In one alternative Alt 7-7-0, which is a sub-alternative of Alt 7-7, yis reported in UCI part 1 via a ┌log ₂ (N₃−M+Z)┐-bit indication. Atleast one of the following is used.

-   -   Z=−1, and the indication indicates a value in {M₁+1, M₁+2, . . .        , N₃−2, N₃−1}    -   Z=0, and the indication indicates a value in {M₁, M₁+1, M₁+2, .        . . , N₃−2, N₃−1}    -   Z=0, and the indication indicates a value in {M₁+1, M₁+2, . . .        , N₃−2, N₃−1,6N₃}    -   Z=1, and the indication indicates a value in {M₁, M₁+1, M₁+2, .        . . , N₃−2, N₃−1, N₃}.

In one alternative Alt 7-9-0, which is a sub-alternative of Alt 7-9,M=┌y×M┐ or y×M and y is determined according to at least one of thefollowing examples.

In one example Ex 7-9-0-0: y is fixed. In one example, y=3/2=1.5. In oneexample, y=2.

In one example Ex 7-9-0-1: y is higher-layer configured.

In one example Ex 7-9-0-1A, y is configured independently (separately)using a separate parameter which takes values from {y₁, y₂}, e.g.,

$\left\{ {y_{1},y_{2}} \right\} = {\left\{ {\frac{3}{2},\frac{5}{4}} \right\}\mspace{14mu}{or}\mspace{14mu}\left\{ {1,\frac{3}{2}} \right\}}$

In one example Ex 7-9-0-1B, y is configured implicitly (i.e., noseparate higher layer parameter is used) via a higher-layer parameter.At least one of the following is used.

-   -   y is configured implicitly via higher layer parameter p. For        example, when p=¼, y=2 and when p=½, y=3/2.    -   y is configured implicitly via higher layer parameter (p, v₀).        For example, for rank 1-2, when p=1/4, y=2 and when p=1/2,        y=3/2; and for rank 3-4, when v₀¼, y=2 and when v₀₌⅛, y=2 or 4.

In one example Ex 7-9-0-1C, y is configured jointly with at least onehigher-layer parameter. At least one of the following is used.

-   -   y is configured jointly with higher layer parameter p

$\left( {p,y} \right) = {\left\{ {\left( {\frac{1}{4},2} \right),\ \left( {\frac{1}{2},\frac{3}{2}} \right)} \right\}.}$

-   -   y is configured jointly with higher layer parameter (p, v₀). At        least one of the following is used.

$\mspace{79mu}{\left( {p,v_{0},y} \right) = {{\left\{ {\left( {\frac{1}{4},\frac{1}{4},2} \right),\left( {\frac{1}{2},\frac{1}{4},\frac{3}{2}} \right)} \right\}.\mspace{79mu}\left( {p,v_{0},y} \right)} = {{\left\{ {\left( {\frac{1}{4},\frac{1}{8},2} \right),\left( {\frac{1}{4},\frac{1}{4},2} \right),\left( {\frac{1}{2},\frac{1}{4},\frac{3}{2}} \right)} \right\}.\mspace{79mu}\left( {p,v_{0},y} \right)} = {{\left\{ {\left( {\frac{1}{4},\frac{1}{8},2} \right),\left( {\frac{1}{2},\frac{1}{4},\frac{3}{2}} \right)} \right\}.\left( {p,v_{0},y} \right)} = \left\{ {\left( {\frac{1}{4},\frac{1}{8},2} \right),\left( {\frac{1}{4},\frac{1}{4},2} \right),\left( {\frac{1}{2},\frac{1}{4},\frac{3}{2}} \right),\left( {\frac{1}{2},\frac{1}{8},\frac{3}{2}} \right)} \right\}}}}}$

In one example Ex 7-9-0-2: y is reported in UCI part 1

In one example Ex 7-9-0-2A: a 1-bit indication is used to indicate oneof the two supported values {y_(i), y₂}. At least one of the followingis used.

-   -   The two supported values are fixed. At least one of the        following is used.        -   {y₁, y₂} is independent of p value, e.g.,

$\left\{ {y_{1},y_{2}} \right\} = {\left\{ {\frac{3}{2},2} \right\}\mspace{14mu}{or}\mspace{14mu}\left\{ {\frac{3}{2},1} \right\}\mspace{14mu}{or}\mspace{14mu}\left\{ {\frac{3}{2},\frac{5}{4}} \right\}}$

-   -   {y₁, y₂} depends on p value, e.g., if

${p = \frac{1}{4}},{\left\{ {y_{1},y_{2}} \right\} = \left\{ {\frac{3}{2},2} \right\}}$

and if

${p = \frac{1}{2}},{\left\{ {y_{1},y_{2}} \right\} = {\left\{ {\frac{3}{2},1} \right\}\mspace{14mu}{or}\mspace{14mu}{\left\{ {\frac{3}{2},\frac{5}{4}} \right\}.}}}$

-   -   The two supported values are higher-layer configured, e.g., from

$\left\{ {\frac{3}{2},\frac{5}{4},1,2} \right\}.$

In one alternative Alt 7-1-0, which is a sub-alternative of Alt 7-1,N′₃=┌y×N₃┐ or y×N₃ or ┌y×N_(SB)┐ or y×N_(SB) and y is determinedaccording to at least one of the following examples.

In one example Ex 7-1-0-0: y is fixed. In one example, y=¾=0.75.

In one example Ex 7-1-0-1: y is higher-layer configured.

In one example Ex 7-1-0-1A, y is configured independently (separately)using a separate parameter which takes values from {y₁, y₂}, e.g.,

$\left\{ {y_{1},y_{2}} \right\} = {\left\{ {\frac{2}{3},\frac{3}{4}} \right\}\mspace{14mu}{or}\mspace{14mu}\left\{ {\frac{5}{8},\frac{3}{4}} \right\}\mspace{14mu}{or}\mspace{14mu}\left\{ {\frac{1}{2},\frac{3}{4}} \right\}\mspace{14mu}{or}\mspace{14mu}\left\{ {1,\frac{3}{4}} \right\}}$

In one example Ex 7-1-0-1B, y is configured implicitly (i.e., noseparate higher layer parameter is used) via a higher-layer parameter.At least one of the following is used.

-   -   y is configured implicitly via higher layer parameter p. At        least one of the following is used.        -   y=p+a, where a is fixed, e.g., a=¼        -   y=a×p, where a is fixed, e.g., a=2    -   y is configured implicitly via higher layer parameter (p, v₀).        At least one of the following is used.        -   y=p+a for rank 1-2 and y=v₀+a for rank 3-4, where a is            fixed, e.g., a=¼        -   y=a×p for rank 1-2 and y=a×v₀ for rank 3-4, where a is            fixed, e.g., a=2

In one example Ex 7-1-0-1C, y is configured jointly with at least onehigher-layer parameter. At least one of the following is used.

-   -   y is configured jointly with higher layer parameter p

$\left( {p,y} \right) = {\left\{ {\left( {\frac{1}{4},\frac{1}{2}} \right),\left( {\frac{1}{2},\frac{3}{4}} \right)} \right\}.}$

-   -   y is configured jointly with higher layer parameter (p, v₀). At        least one of the following is used.

$\mspace{79mu}{\left( {p,v_{0},y} \right) = {{\left\{ {\left( {\frac{1}{4},\frac{1}{4},\frac{1}{2}} \right),\left( {\frac{1}{2},\frac{1}{4},\frac{3}{2}} \right)} \right\}.\mspace{79mu}\left( {p,v_{0},y} \right)} = {{\left\{ {\left( {\frac{1}{4},\frac{1}{8},\frac{1}{2}} \right),\left( {\frac{1}{4},\frac{1}{4},\frac{1}{2}} \right),\left( {\frac{1}{2},\frac{1}{4},\frac{3}{2}} \right)} \right\}.\mspace{79mu}\left( {p,v_{0},y} \right)} = {{\left\{ {\left( {\frac{1}{4},\frac{1}{8},\frac{1}{2}} \right),\left( {\frac{1}{2},\frac{1}{4},\frac{3}{2}} \right)} \right\}.\left( {p,v_{0},y} \right)} = \left\{ {\left( {\frac{1}{4},\frac{1}{8},\frac{1}{2}} \right),\left( {\frac{1}{4},\frac{1}{4},\frac{1}{2}} \right),\left( {\frac{1}{2},\frac{1}{4},\frac{3}{2}} \right),\left( {\frac{1}{2},\frac{1}{8},\frac{3}{2}} \right)} \right\}}}}}$

In one example Ex 7-1-0-2: y is reported in UCI part 1

In one example Ex 7-1-0-2A: a 1-bit indication is used to indicate oneof the two supported values {y₁, y₂}. At least one of the following isused.

-   -   The two supported values are fixed. At least one of the        following is used.        -   {y₁, y₂} is independent of p value, e.g.,

$\left\{ {y_{1},y_{2}} \right\} = {\left\{ {\frac{2}{3},\frac{3}{4}} \right\}\mspace{14mu}{or}\mspace{14mu}\left\{ {\frac{5}{8},\frac{3}{4}} \right\}\mspace{14mu}{or}\mspace{14mu}\left\{ {\frac{1}{2},\frac{3}{4}} \right\}}$

-   -   {y₁, y₂} depends on p value, e.g., if

${p = \frac{1}{4}},{\left\{ {y_{1},y_{2}} \right\} = \left\{ {\frac{1}{2},\frac{3}{4}} \right\}}$

and if

${p = \frac{1}{2}},{\left\{ {y_{1},y_{2}} \right\} = {\left\{ {\frac{2}{3},\frac{3}{4}} \right\}\mspace{14mu}{or}\mspace{14mu}{\left\{ {\frac{5}{8},\frac{3}{4}} \right\}.}}}$

-   -   The two supported values are higher-layer configured, e.g., from

$\left\{ {\frac{1}{2},\frac{5}{8},\frac{2}{3},\frac{3}{4},1} \right\}.$

In one alternative Alt 7-10, N′₃=y(M+N₃) or ┌y(M+N₃)┐ or └y(M+N₃)┘, andy is determined according to at least one of the following examples.

In one example Ex 7-10-0: y is fixed. In one example, y=½.

In one example Ex 7-10-1: y is higher-layer configured from {y₁, y₂},e.g.,

$\left\{ {y_{1},y_{2}} \right\} = \left\{ {\frac{1}{2},\frac{3}{4}} \right\}$

In one example Ex 7-10-2: y is reported in UCI part 1

In one example Ex 7-10-2A: a 1-bit indication is used to indicate one ofthe two supported values {y₁, y₂}. At least one of the following isused.

-   -   The two supported values are fixed, e.g.,

$\left\{ {y_{1},y_{2}} \right\} = \left\{ {\frac{1}{2},\frac{3}{4}} \right\}$

-   -   The two supported values are higher-layer configured, e.g., from

$\left\{ {\frac{1}{2},\frac{3}{4},\frac{2}{3}} \right\}.$

In one alternative Alt 7-10A, N′₃ is a fixed value satisfying M<N′₃<N₃,e.g.,

$N_{3}^{\prime} = {\frac{M + N_{3}}{2}\mspace{14mu}{or}\mspace{14mu}\left\lceil \frac{M + N_{3}}{2} \right\rceil\mspace{20mu}{or}\mspace{20mu}{\left\lfloor \frac{M + N_{3}}{2} \right\rfloor.}}$

In embodiment 8, for RI≥1, the value N′₃ to determine the size of the FDintermediate basis set is determined according to at least one of thefollowing alternatives.

In one alternative Alt 8-0: N′₃ is RI-common and layer-common, i.e., asingle N′₃ is used for all RI values, and for all layers.

In one alternative Alt 8-1: M is RI-common and layer-specific, i.e., aseparate N′₃ value is used for each layer value, and for a given layervalue, the N′₃ value is common for all ranks or RI values.

In one alternative Alt 8-2: N′₃ is RI-specific and layer-common, i.e., aseparate N′₃ is used for each rank or RI value, and for a given RIvalue, the N′₃ value is common for all layers. For example, N′₃=N₃ forrank 1-2 (i.e., FD basis selection is according to embodiment 0) and N′₃is according to Alt 7-9 for rank 3-4 (i.e., FD basis selection isaccording to embodiment 1-5).

In one alternative Alt 8-3: N′₃ is RI-specific and layer-specific, i.e.,a separate N′₃ value is used for each layer value and for each rank orRI value.

In embodiment 9, the size-N′₃ FD intermediate basis set is determinedaccording to at least one of the following alternatives.

In one alternative Alt 9-0: the size-N′₃ FD intermediate basis set isadjacent and fully parameterized with the starting index M_(initial) ofthe intermediate basis set (cf. embodiment 1). In one example,M_(initial) is reported in UCI part 2.

In one alternative Alt 9-1: the size-N′₃ FD intermediate basis set isselected freely from N3 FD bases using a

$\left\lceil {\log_{2}\begin{pmatrix}N_{3} \\N_{3}^{\prime}\end{pmatrix}} \right\rceil\text{-}{bit}$

combinatorial indicator, which for example, is reported in UCI part 2.

In one alternative Alt 9-2: the size-N′₃ FD intermediate basis set isselected from a number of higher-layer configured candidate subsets.

In one alternative Alt 9-3: the size-N′₃ FD intermediate basis set isselected freely from N3 FD bases using an N₃-bit bitmap, which forexample, is reported in UCI part 2. The bitmap (bit sequence) compriseN′₃ ones “1” and remaining zeros “0”, where the locations of onescorrespond to the indices of the N′₃ intermediate FD bases.Alternatively, the bitmap (bit sequence) comprise N′₃ zeros “0” andremaining ones “1”, where the locations of zeros correspond to theindices of the N′₃ intermediate FD bases.

In Embodiment 10, for RI >1, the FD intermediate basis set is determinedaccording to at least one of the following alternatives.

In one alternative Alt 10-0: the FD intermediate basis set is RI-commonand layer-common, i.e., a single FD intermediate basis set is used forall RI values, and for all layers.

In one alternative Alt 10-1: the FD intermediate basis set is RI-commonand layer-specific, i.e., a separate FD intermediate basis set is usedfor each layer value, and for a given layer value, the FD intermediatebasis set is common for all ranks or RI values.

In one alternative Alt 10-2: the FD intermediate basis set isRI-specific and layer-common, i.e., a separate FD intermediate basis setis used for each rank or RI value, and for a given RI value, the FDintermediate basis set is common for all layers.

In one alternative Alt 10-3: the FD intermediate basis set isRI-specific and layer-specific, i.e., a separate FD intermediate basisset is used for each layer value and for each rank or RI value.

In embodiment 11, each PMI value, indicating the precoder or precodingmatrix according to the framework (5), corresponds to the codebookindices i₁ and i₂ where

 

where

-   -   i_(1, 1) are the rotation factors for the SD basis (same as in        Rel. 15 Type II CSI codebook)    -   i_(1, 2) is the SD basis indicator (same as in Rel. 15 Type II        CSI codebook)    -   i_(1, 5) is the M_(initial) indicator when N₃>19, indicating the        intermediate FD basis set InS comprising 2M FD basis vectors    -   i_(1, 6, l) is the FD basis indicator for layer l, indicating M        FD basis vectors    -   i_(1, 7, l) is the bitmap for layer l, indicating the location        of non-zero (NZ) coefficients    -   i_(1, 8, l) is the strongest coefficient indicator (SCI) for        layer l, indicating location of the strongest coefficient=1    -   i_(2, 3, 1) are the reference amplitudes (p_(lr) ⁽¹⁾) for layer        l, indicating the reference amplitude coefficient for the weaker        polarization    -   i_(2, 4, l) is the matrix of the differential amplitude values        (p_(l, i, m) ⁽²⁾ for layer l    -   i_(2, 5, l) is the matrix of the phase values (φ_(i,i,m)) for        layer l

In embodiment 12, a UE is configured to report the FD basis vectors forl=1, 2, . . . , v, where v is the rank value (or number of layers)indicated by RI, according to embodiment 6, Alt 6-0 with x=19 of thisdisclosure, i.e.,

-   -   If N₃≤19, the FD basis vectors are reported according to (A),        i.e., without using any FD intermediate basis set InS (cf.        embodiment 0), and    -   If N₃>19, the FD basis vectors are reported according to (B),        i.e., using an FD intermediate basis set InS (cf. embodiment 1).

The size of the InS is according to Alt 7-9-0, i.e., N′₃┌y×M┐ or y×M andy is fixed to y=2. The value N′₃ is according to Alt 8-2, i.e.,layer-common but depends on the M value for different ranks. Forexample, let

${M = \left\lceil {p\frac{N_{3}}{R}} \right\rceil},$

where R is higher layer configured, then p=y₀ value for rank 1-2 andp=v₀ value for rank 3-4 can be different, e.g.,

$\left( {y_{0},v_{0}} \right) \in {\left\{ {\left( {\frac{1}{4},\frac{1}{8}} \right),\left( {\frac{1}{4},\frac{1}{4}} \right),\left( {\frac{1}{2},\frac{1}{4}} \right)} \right\}.}$

The size-N′₃ FD intermediate basis set InS is determined according toAlt 9-0 (cf. embodiment 1), i.e., InS is fully parameterized with thestarting index M_(initial) of the intermediate basis set (cf. embodiment1). The indices of the FD basis vectors in InS is given bymod(M_(initial)+n, N₃), n=0, 1, . . . , N′₃−1, InS is RI-common andlayer-common (cf. Alt 10-0), and M_(initial) is reported via a┌log₂X┐-bit indicator (cf. Alt 1C-0) where X=N₃ or N′₃. For each layerl∈{0, 1, . . . , v−1}, one of the FD basis vectors is always fixed,hence not reported by the UE. In one example, this fixed FD basis vectoris FD basis vector with index=0. The remaining M_(l)−1 FD basis vectorsare selected/reported by the UE as follows.

-   -   If N₃≤19: the remaining M_(l)−1 FD basis vectors are        selected/reported according to Alt 0-1, i.e., the FD basis        subset selection indicator i_(FD, l) is a

$\left\lceil {\log_{2}\begin{pmatrix}{N_{3} - 1} \\{M_{l} - 1}\end{pmatrix}} \right\rceil\text{-}{bit}$

indicator,where

$i_{1} = \left\{ {{\begin{matrix}{\left\lbrack {i_{1,1}\mspace{14mu} i_{1,2}\mspace{14mu} i_{1,5}\mspace{14mu} i_{1,6,1}\mspace{20mu} i_{1,7,1}\mspace{14mu} i_{1,8,1}} \right\rbrack} & {\upsilon = 1} \\{\left\lbrack {i_{1,1}\mspace{14mu} i_{1,2}\mspace{14mu} i_{1,5}\mspace{14mu} i_{1,6,1}\mspace{20mu} i_{1,7,1}\mspace{14mu} i_{1,8,1}\mspace{14mu} i_{1,6,2}\mspace{14mu} i_{1,7,2}\mspace{14mu} i_{1,8,2}} \right\rbrack} & {\upsilon = 2} \\{\left\lbrack {i_{1,1}\mspace{14mu} i_{1,2}\mspace{14mu} i_{1,5}\mspace{14mu} i_{1,6,1}\mspace{20mu} i_{1,7,1}\mspace{14mu} i_{1,8,1}\mspace{14mu} i_{1,6,2}\mspace{14mu} i_{1,7,2}\mspace{14mu} i_{1,8,2}\mspace{14mu} i_{1,6,3}\mspace{20mu} i_{1,7,3}\mspace{20mu} i_{1,8,3}} \right\rbrack} & {\upsilon = 3} \\{\left\lbrack {i_{1,1}\mspace{14mu} i_{1,2}\mspace{14mu} i_{1,5}\mspace{14mu} i_{1,6,1}\mspace{20mu} i_{1,7,1}\mspace{14mu} i_{1,8,1}\mspace{14mu} i_{1,6,2}\mspace{14mu} i_{1,7,2}\mspace{14mu} i_{1,8,2}\mspace{14mu} i_{1,6,3}\mspace{20mu} i_{1,7,3}\mspace{20mu} i_{1,8,3}\mspace{14mu} i_{1,6,4}\mspace{14mu} i_{1,7,4}\mspace{20mu} i_{1,8,4}} \right\rbrack} & {\upsilon = 4}\end{matrix}\mspace{20mu} i_{1}} = \left\{ \begin{matrix}{\left\lbrack {i_{2,3,1}\mspace{20mu} i_{2,4,1}\mspace{20mu} i_{2,5,1}} \right\rbrack} & {\upsilon = 1} \\{\left\lbrack {i_{2,3,1}\mspace{20mu} i_{2,4,`}\mspace{20mu} i_{2,5,1}\mspace{20mu} i_{2,3,2}\mspace{20mu} i_{2,4,2}\mspace{14mu} i_{2,5,2}} \right\rbrack} & {\upsilon = 2} \\{\left\lbrack {i_{2,3,1}\mspace{20mu} i_{2,4,1}\mspace{20mu} i_{2,5,1}\mspace{20mu} i_{2,3,2}\mspace{20mu} i_{2,4,2}\mspace{20mu} i_{2,5,2}\mspace{14mu} i_{{2,3,3}\;}\mspace{14mu} i_{2,4,3}\mspace{20mu} i_{2,5,3}} \right\rbrack} & {\upsilon = 3} \\{\left\lbrack {i_{2,3,1}\mspace{20mu} i_{2,4,1}\mspace{20mu} i_{2,5,1}\mspace{20mu} i_{2,3,2}\mspace{20mu} i_{2,4,2}\mspace{20mu} i_{2,5,2}\mspace{14mu} i_{{2,3,3}\;}\mspace{14mu} i_{2,4,3}\mspace{20mu} i_{2,5,3}\mspace{14mu} i_{2,3,4}\mspace{20mu} i_{2,4,4}\mspace{20mu} i_{2,5,4}} \right\rbrack} & {\upsilon = 4}\end{matrix} \right.} \right.$

-   -   If N₃>19: the remaining M_(l)−1 FD basis vectors are        selected/reported according to Alt 1-1, i.e., the FD basis        subset selection indicator i_(FD, l) is a

$\left\lceil {\log_{2}\begin{pmatrix}{N_{3} - 1} \\{M_{l} - 1}\end{pmatrix}} \right\rceil\text{-}{bit}$

indicator,where

$i_{{FD},l} \in {\left\{ {0,1,\ldots\;,{\begin{pmatrix}{N_{3}^{\prime} - 1} \\{M_{l} - 1}\end{pmatrix} - 1}} \right\}.}$

The above description of FD basis vector selection/indication/reportingis equivalent to the following more detailed description.

The M FD basis vectors combined by the codebook are identified by theindices, n_(3, l) (l=1, . . . , v), and M_(initial) (for N₃>19), where

n _(3, l)=[b _(3, l) ⁽⁰⁾ l , . . . , n _(3, l) ^(M−1))],

n _(3, l) ^((m))∈{0, 1, . . . , N ₃−1},

M _(initial)∈{−2M+1, −2M+2, . . . , 0},

which are indicated (reported) by means of the indices i_(1, 5)indicating M_(initial) (for N₃>19) and i_(1, 6, l) indicaing n_(3, l)(1=1, . . . , v), where

${i_{1,5} \in \left\{ {0,1,\ldots\;,{{2M} - 1}} \right\}},{i_{1,6,l} \in \left\{ {\begin{matrix}\left\{ {0,1,\ldots\;,{\begin{pmatrix}{N_{3} - 1} \\{M - 1}\end{pmatrix} - 1}} \right\} & {N_{3} \leq 19} \\\left\{ {0,1,\ldots\;,{\begin{pmatrix}{N_{3}^{\prime} - 1} \\{M - 1}\end{pmatrix} - 1}} \right\} & {N_{3} > 19}\end{matrix},{N_{3}^{\prime} = {2{M.}}}} \right.}$

For N₃>19, M_(initial) is identified by i_(1. 5) as follows

$M_{initial} = \left\{ {\begin{matrix}i_{1,5} & {i_{1,5} = 0} \\{i_{1,5} - {2M}} & {i_{1,5} > 0}\end{matrix}.} \right.$

As described in U.S. patent application Ser. No. 16/045,543, filed Jul.25, 2018 and entitled “Method and Apparatus for Beam Selection for CSIReporting in Advanced Wireless Communication Systems,” which isincorporated herein by reference in its entirety, the indices of FDbasis vectors can be reported jointly using a single indicator. Inparticular, for all values of N₃, n_(3, l) ⁽⁰⁾=0 for l=1, . . . , v,indicating that the FD basis vector with index=0 is always included. Theremaining M−1 nonzero elements of n_(3, l), identified by n_(3, l) ⁽¹⁾,. . . , n_(3, l) ^((M−1)), are found from i_(1, 6, l) (l=1, . . . , v),for N₃<19, and from i_(1, 6, l) (l=1, . . . , v) and M_(initiail), forN₃>19, using C(x, y) as defined in 5.2.2.2.3 of [REFS] and thealgorithm:

  s₀ = 0 for m = 1, ..., M − 1 Find the largest x* ϵ {M − 1 − m, ..., N₃ − 1 − m} in Table B-1 such that  i_(1,6,l) − s_(m−1) ≥ C(x*, M − m) e_(m) = C(x*, M − m)  s_(m) = s_(m−1) + e_(m)  if N₃ ≤ 19  n_(3,l)^((m)) = N₃ − 1 − x* else  n_(l) ^((m)) = 2M − 1 − x*  if n_(l) ^((m)) ≤M_(initial) + 2M − 1   n_(3,l) ^((m)) = n_(l) ^((m))  else   n_(3,l)^((m)) = n_(l) ^((m)) + (N₃ − 2M)  end if end if

TABLE B-1 Combinatorial coefficients C(x, y) y x 1 2 3 4 5 6 7 8 9 0 0 00 0 0 0 0 0 0 1 1 0 0 0 0 0 0 0 0 2 2 1 0 0 0 0 0 0 0 3 3 3 1 0 0 0 0 00 4 4 6 4 1 0 0 0 0 0 5 5 10 10 5 1 0 0 0 0 6 6 15 20 15 6 1 0 0 0 7 721 35 35 21 7 1 0 0 8 8 28 56 70 56 28 8 1 0 9 9 36 84 126 126 84 36 9 110 10 45 120 210 252 210 120 45 10 11 11 55 165 330 462 462 330 165 5512 12 66 220 495 792 924 792 495 220 13 13 78 286 715 1287 1716 17161287 715 14 14 91 364 1001 2002 4004 3432 3003 2002 15 15 105 455 13653003 5005 6435 6435 5005 16 16 120 560 1820 4368 8008 11440 12870 1144017 17 136 680 2380 6188 12376 19448 24310 24310 18 18 153 816 3060 856818564 31824 43758 48620

When n_(3, l) and M_(initial) are known, i_(1, 5) and i_(1, 6, l) (l=1,. . . , v) are found as follows:

-   -   If N₃<19, i_(1, 5)=0 and is not reported. i_(1, 6, l)Σ_(m=1)        ^(M−1) C(N₃−1−n_(3, l) ^((m)), M−m), where C(x, y) is given in        Table B-1 and where the indices m=1, . . . , M−1 are assigned        such that n_(3, l) ^((m)) increases as m increases.    -   If N₃>19, M_(initial) is indicated by i_(1, 5), which is        reported and given by

$i_{1,5} = \left\{ {\begin{matrix}M_{initial} & {M_{initial} = 0} \\{M_{initial} + {2M}} & {M_{initial} < 0}\end{matrix}.} \right.$

Only the nonzero indices n_(3, l) ^((m))∈IntS, whereIntS={(M_(initial)+i) mod N₃, i=0, 1, . . . ,2M−1}, are reported, wherethe indices m=1, . . . , M−1 are assigned such that n_(3, l) ^((m))increases as m increases. Let

$n_{l}^{(m)} = \left\{ {\begin{matrix}n_{3,l}^{(m)} & {n_{3,l}^{(m)} \leq {M_{initial} + {2M} - 1}} \\{m_{3,l}^{(m)} - \left( {N_{3} - {2M}} \right)} & {n_{3,l}^{(m)} > {M_{initial} + N_{3} - 1}}\end{matrix},} \right.$

then i_(1, 6, l) =Σ_(m=1) ^(M−1) C(2M−1−n_(l) ^((m)), M−m), where C(x,y) is given in Table B-1.

FIG. 14 illustrates a window-based intermediate basis set 1400 accordingto embodiments of the present disclosure. The embodiment of thewindow-based intermediate basis set 1400 illustrated in FIG. 14 is forillustration only. FIG. 14 does not limit the scope of this disclosureto any particular implementation of the window-based intermediate basisset 1400.

In embodiment 13, a two-step FD basis subset selection method is used.The first step uses an intermediate FD basis set comprising M basisvectors (where N′₃≤N₃). The value N′₃ is either reported by the UE(e.g., via part 1 of a two-part UCI) or fixed or higher-layerconfigured. The intermediate FD basis set is a common pool of FD basisvectors for all layers, and is reported via part 2 of a two-part UCI.The indices of the FD basis vectors in this intermediate set is given bymod(M_(initial)+n, N₃), n=0, 1, . . . , N′₃−1, which corresponds to awindow-based intermediate basis set 1400 as illustrated in FIG. 14comprising N′₃ adjacent FD indices with modulo-shift by N₃, whereM_(initial) is the starting index of the intermediate FD basis set.

In the second step, for each layer l∈{0, 1, . . . , v−1}, the set ofM_(l) FD basis vectors are reported by the UE from the intermediate FDbasis set according to at least one of the following alternatives.

In one alternative Alt 13-0: the FD basis subset selection indicatori_(FD, l) is a

$\left\lceil {\log_{2}\begin{pmatrix}N_{3}^{\prime} \\M_{l}\end{pmatrix}} \right\rceil\text{-}{bit}$

indicator, where

$i_{{FD},l} \in {\left\{ {0,1,\ldots\mspace{14mu},{\begin{pmatrix}N_{3}^{\prime} \\M_{l}\end{pmatrix} - 1}} \right\}.}$

In one alternative Alt 13-1: the FD basis subset selection indicatori_(FD, l) is a

$\left\lceil {\log_{2}\begin{pmatrix}N_{3}^{\prime} \\{M_{l} - 1}\end{pmatrix}} \right\rceil\mspace{20mu}{or}\mspace{20mu}\left\lceil {\log_{2}\begin{pmatrix}{N_{3}^{\prime} - 1} \\{M_{l} - 1}\end{pmatrix}} \right\rceil\text{-}{bit}$

indicator, where

$i_{{FD},l} \in {\left\{ {0,1,\ldots\;,{\begin{pmatrix}N_{3}^{\prime} \\{M_{l} - 1}\end{pmatrix} - {1\mspace{14mu}{or}\mspace{14mu}\begin{pmatrix}{N_{3}^{\prime} - 1} \\{M_{l} - 1}\end{pmatrix}} - 1}} \right\}.}$

In this alternative, one of the FD basis vectors is always fixed, andhence not reported by the UE. In one example, this fixed FD basis vectoris FD basis vector with index=0.

In one alternative Alt 13-2: the FD basis subset selection indicatori_(FD, l) is a size-N′₃ bitmap, where i_(FD, l)=b₀b₁. . . b_(N′) ₃ , andthe set of M_(l) FD basis vectors are indicated by reporting M_(l) ofthese bits b_(i)'s to one and the rest to zero. Alternatively, the setof M_(l) FD basis vectors are indicated by reporting M_(l) of these bitsb_(i)'s to zero and the rest to one.

In embodiment 13A, the starting index (M_(initial)) of the intermediateFD basis set is indicated (reported) by the UE (e.g., via part 2 UCI).In one example, this indication is via a ┌log₂ N₃┐-bit indicator.

In embodiment 13B, the starting index (M_(initial)) of the intermediateFD basis set is fixed, hence not reported by the UE. In one example,M_(initial)=0. At least one of the following alternatives is used todetermine (obtain) the intermediate basis set.

In one alternative Alt13B-1, the intermediate basis set (denoted as InS)is determined based on layer-specific InS(1) of size N′₃ as follows.

-   -   For each layer l∈{0, 1, . . . , RI−1}, the UE determines a        window-based InS(l) (comprising N′₃ components out of N₃ FD        basis vectors) with the starting index M_(initial, l). In one        example, this determination is based on max power. For example,        -   The UE calculates the power p_(n) of each FD component n∈{0,            1, . . . , N₃'1} using the DL channel measurements.        -   The UE then calculates sum power of S_(n)=∈_(k=0) ^(N′) ³ ⁻¹            p_(n+k) for each n∈ {0, 1, . . . , N₃−1}.        -   The starting index M_(initial, l)=n* where n* is the index n            such that

$S_{n^{*}} = {\max\limits_{n \in {\{{0,\mspace{11mu}\ldots\mspace{11mu},{N_{3} - 1}}\}}}{S_{n}.}}$

-   -   In one example, the UE is restricted to determine the InS(l) for        layers such that M_(initial, l) for all layers are restricted to        be within a value Δ. In one example,

$M_{{initial},l} \in \left\{ {N_{3} - \frac{N_{3}^{\prime}}{2} + \Delta} \right\}$

where Δ is fixed, e.g., Δ={−2, −1, 0, 1, 2}.

-   -   InS′ with M_(initial) as starting index is then determined based        on {M_(initial, 0), M_(initial, 1), . . . , M_(initial, RI−1)}        -   In one example, M′_(initial)=min{M_(initial, 0),            M_(initial, 1), . . , M_(initial, R1−1)}        -   In one example, M′_(initial)=M_(initial, Z) where Z is            fixed, e.g., Z=0 or RI−1        -   In one example, M′_(initial)=M_(initial, Z) where Z is            configured from {0, . . . , RI−1}.        -   In one example, M′_(initial)=M_(initial, Z) where Z is            reported by the UE, e.g., from {0, . . . , RI−1}.    -   Let

{k_(n)}_(n = 0)^(N₃^(′) − 1)

be the FD indices comprising InS with M′_(initial) as the startingindex.

-   -   Finally, InS with M_(initial)=0 is determined by modulo cyclic        shift (CS) of InS′ where the amount of CS x=M′_(initial). The        modulo-shifted FD indices is given by

{k_(n)^(′) = mod{k_(n) − x, N₃}}_(n = 0)^(N₃^(′) − 1).

In one alternative Alt13B-2, the intermediate basis set (denoted as InS)is determined based on layer-specific InS(l) of size M_(l) as follows.

-   -   For each layer l∈{0, 1, . . . , RI−1}, the UE determines a        window-based InS(l) (comprising M_(l) components out of N₃ FD        basis vectors) with the starting index M_(initial, l). In one        example, this determination is based on max power. For example,        -   The UE calculates the power p_(n) of each FD component n∈{0,            1, . . . , N³⁻1} using the DL channel measurements.        -   The UE then calculates sum power of S_(n)=Σ_(k=0) ^(M) ^(l)            ⁻¹ p_(n+k) for each ∈ {0, 1, . . . , N₃−1}.        -   The starting index            M_(initial, l=n* where n* is the index n such that)

$S_{n^{*}} = {\max\limits_{n\;\epsilon{\{{0,\ldots\;,{N_{3} - 1}}\}}}{S_{n}.}}$

-   -   In one example, the UE is restricted to determine the InS(l) for        layers such that M_(initial, l) for all layers are restricted to        be within a value Δ. In one example,

$M_{{initial},l} \in \left\{ {N_{3} - \frac{N_{3}^{\prime}}{2} + \Delta} \right\}$

where Δ is fixed, e.g., ΔA={−2, −1, 0, 1, 2}.

-   -   InS' with ML_(itt&) as starting index is then determined based        on {M_(initial, 0), M_(initial, 1), M_(initial, RI−1})        -   In one example, M′_(initial)=Min{M_(initial, 0),            M_(initial, 1), M_(initial, R−)1}    -   Let

{k_(n)}_(n = 0)^(N₃^(′) − 1)

be the FD indices comprising InS with M′_(initial) as starting index.

-   -   Finally, InS with M_(initial)=0 is determined by modulo cyclic        shift (CS) of InS′ where the amount of CS x=M′_(initial). The        modulo-shifted FD indices is given by

{k_(n)^(′) = mod{k_(n) − x, N₃}}_(n = 0)^(N₃^(′) − 1).

In one alternative Alt13B-3, the intermediate basis set (denoted as InS)is determined as follows.

-   -   For each layer l∈{0, 1, . . . , RI−1}, the UE determines the LC        coefficients {c_(l, i, m)} for all i∈{0, 1, . . . ,2L−1} and        m∈{0, 1, . . . , N₃−1}.    -   For each FD index m∈{0, 1, . . . , N₃−1}, the UE calculates a        metric value p_(m) using the LC coefficients {c_(l, i, m)}. In        one example, the metric is (sum) power p_(m)=Σ_(l=0) ^(RI−1)        Σ_(i=0) ^(2L−1) a_(l, i, m) where a_(l, i, m)=|c_(l, i, m)| is        the amplitude of the coefficient c_(l, i, m). Note that the sum        is over all layers and all spatial domain (SD) basis (or beams).    -   The UE calculates sum power for all possible window-based        intermediate basis sets, i.e., the UE computes S_(m)=Σ_(n=0)        ^(N′) ³ ¹ p_(m+n) for each m E∈{0, 1, . . . , N₃−1}.    -   The UE then determines InS′ with starting index M′_(initial)=m*,        where m* is the index m such that

$S_{m^{*}} = {\max\limits_{m\;\epsilon{\{{0,\ldots\;,{N_{3} - 1}}\}}}{S_{m}.}}$

Let

{k_(n)}_(n = 0)^(N₃^(′) − 1)

be the FD indices comprising InS′ with M_(initial)=m* as starting index.

-   -   Finally, InS with M_(initial)=0 is determined by modulo cyclic        shift (CS) of InS′ where the amount of CS x=M′_(initial). The        modulo-shifted FD indices is given by

{k_(n)^(′) = mod{k_(n) − x, N₃}}_(n = 0)^(N₃^(′) − 1).

In a variation, when N′₃ value is not sufficient to capture all“dominant” FD indices for all layers (which correspond to FD indiceswith large power), then UE can set N′₃=N₃ and select all FD components{0, 1, . . . , N₃−1} in InS. Note that this selection is equivalent toone-step FD basis selection. The UE can indicate (report) this selectionvia a 1-bit indication I in UCI part 1.

-   -   In one example, I=0 indicates N′₃=N₃ or one-step FD basis        selection, and I=1 indicates N′₃<N₃ or two-step FD basis        selection.    -   In another example, I=1 indicates N′₃=N₃ or one-step FD basis        selection, and I=0 indicates N′₃<N₃ or two-step FD basis        selection.

In one alternative Alt13B-4, the intermediate basis set (denoted as InS)is determined as follows.

-   -   For each layer l∈{0, 1, . . . , RI−1}, the UE determines the        indices {k_(m) _(l) }_(m) _(l) ₌₀ ^(M) ^(l) ⁼¹ indicating the FD        basis

W_(f) = [w_(k₀), w_(k₁) , …  , w_(k_(M_(l) − 1))]

and the LC coefficients {c_(l, i, m)}, where M_(l)<N₃ is the number ofFD basis vectors selected for layer l.

-   -   For each FD index m∈{0, 1, . . . , N₃−1}, the UE calculates a        metric value p_(m) using the LC coefficients {c_(l, i, m)}. In        one example, the metric is (sum) power p_(m)=Σ_(l−0) ^(RI−1)        Σ_(i=0) ^(2L−1) a_(l, i, m) where a_(l, i, m)=|c_(l, i, m)| is        the amplitude of the coefficient c_(l, i, m) and the UE sets        c_(l, i, m)=0 for FD indices which don't belong to the set of        indices

{k_(m_(l))}_(m_(l) = 0)^(M_(l) − 1).

Note that the sum is over all layers and all spatial domain (SD) basis(or beams).

-   -   The UE calculates sum power for all possible window-based        intermediate basis sets, i.e., the UE computes S_(m)=Σ_(n=0)        ^(N′) ³ ⁻¹p_(m+n) for each m∈{0, 1, . . . , N₃−1}.    -   The UE then determines InS′ with starting index M′_(initial)=m*,        where m* is the index m such that

$S_{m}^{*} = {\max\limits_{0,{m \in {\{{0,\ldots\mspace{14mu},{N_{3} - 1}}\}}}}{S_{m}.}}$

Let {k_(n)}_(n=0) ^(N′) ³ ⁻¹ be the FD indices comprising InS′ withM′_(initial)=m* as starting index.

-   -   Finally, InS with M_(initial)=0 is determined by modulo cyclic        shift (CS) of InS′ where the amount of CS x=M′_(initial). The        modulo-shifted FD indices is given by

{k_(n)^(′) = mod{k_(n) − x, N₃}}_(n = 0)^(N₃^(′) − 1).

In a variation, when N′₃ value is not sufficient to capture all“dominant” FD indices for all layers (which correspond to FD indiceswith large power), then UE can set N′₃=N₃ and select all FD components{0, 1, . . . , N₃−1} in InS. Note that this selection is equivalent toone-step FD basis selection. The UE can indicate (report) this selectionvia a 1-bit indication I in UCI part 1.

-   -   In one example, I=0 indicates N′₃=N₃ or one-step FD basis        selection, and I=1 indicates N′₃<N₃ or two-step FD basis        selection.    -   In another example, I=1 indicates N′₃=N₃ or one-step FD basis        selection, and I=0 indicates N′₃<N₃ or two-step FD basis        selection.

FIG. 15 illustrates a flow chart of a method 1500 for operating a userequipment (UE), as may be performed by a UE such as UE 116, according toembodiments of the present disclosure. The embodiment of the method 1500illustrated in FIG. 15 is for illustration only. FIG. 15 does not limitthe scope of this disclosure to any particular implementation.

As illustrated in FIG. 15, the method 1500 begins at step 1502. In step1502, the UE (e.g., 111-116 as illustrated in FIG. 1), in response to acondition being satisfied, selects, from a full basis set, a basissubset comprising M_(l) bases for each layer l of a plurality of vlayers.

In step 1504, the UE, in response to the condition not being satisfied,selects, from the full basis set, an intermediate basis set (IntS)comprising N′ bases that are common among the plurality of v layers, andselecting, from the selected intermediate basis set, the basis subsetcomprising M_(l) bases for each layer l of the plurality of v layers.

In step 1506, the UE transmits, to a base station (BS), for each layer lof the plurality of v layers, an indicator i_(1, 6, l) indicatingindices of the M_(l) bases included in the selected basis subset.

In step 1508, the UE, based on the condition not being satisfied,transmits, to the BS, an indicator i_(1, 5) indicating indices of the N′bases included in the selected intermediate basis set (IntS).

The full basis set comprises N₃ bases, wherein N₃, N′, and M_(l) arepositive integers; M_(l)<N₃ when the condition is satisfied andM_(l)<N′<N₃ when the condition is not satisfied; l∈{1, . . . , v}; andv≥1 is a rank value.

In one embodiment, when a value of N₃ is less than or equal to nineteen(N₃≤19), the condition is satisfied; and when the value of N₃ is greaterthan nineteen (N₃>19), the condition is not satisfied.

In one embodiment, one of the indices of the M_(l) bases included in theselected basis subset is fixed to zero for each layer l of the pluralityof v layers; the indicator i_(1, 6, l) indicates the indices of theremaining M_(l)−1 bases included in the selected basis subset for eachlayer l of the plurality of v layers, wherein a payload of the indicatori_(1, 6, l) is

$\left\lceil {\log_{2}\begin{pmatrix}{N_{3} - 1} \\{M_{l} - 1}\end{pmatrix}} \right\rceil\mspace{14mu}{bits}$

when the condition is satisfied and

$\left\lceil {\log_{2}\begin{pmatrix}{N^{\prime} - 1} \\{M_{l} - 1}\end{pmatrix}} \right\rceil\mspace{14mu}{bits}$

when the condition is not satisfied, and ┌ ┐ is a ceiling function; andwhen the condition is not satisfied, the indicator i_(1, 5) indicates aninitial basis index (M_(initial)) of the intermediate basis set (IntS),which is determined as IntS={(M_(initial)+i) mod N₃, i=0, 1, . . . ,N′−1}, where mod is a modulo function.

In one embodiment, the full basis set is a set of discrete Fouriertransform (DFT) vectors:

${w_{n} = \begin{bmatrix}1 & e^{j\frac{2\pi n}{N_{3}}} & e^{2j\frac{2\pi n}{N_{3}}} & \ldots & e^{{({N_{3} - 1})}j\frac{2\pi n}{N_{3}}}\end{bmatrix}},$

where n=0, 1, . . . , N₃−1; and a value of N′ is such that N′=2M_(l).

FIG. 16 illustrates a flow chart of another method 1600, as may beperformed by a base station (BS) such as BS 102, according toembodiments of the present disclosure. The embodiment of the method 1600illustrated in FIG. 16 is for illustration only. FIG. 16 does not limitthe scope of this disclosure to any particular implementation.

As illustrated in FIG. 16, the method 1600 begins at step 1602. In step1602, the BS (e.g., 101-103 as illustrated in FIG. 1), receives, from auser equipment (UE), for each layer l of a plurality of v layers, anindicator i_(1, 6, l) indicating indices of M_(l) bases included in abasis subset.

In step 1604, the BS, based on a condition not being satisfied, receivesan indicator i_(1, 5) indicating indices of N′ bases included in anintermediate basis set (IntS).

In step 1606, the BS, when the condition is satisfied, uses theindicator i_(1, 6, l) to determine, from a full basis set, M_(l) basesincluded in the basis subset for each layer l of the plurality of vlayers.

In step 1608, the BS, when the condition is not satisfied, uses theindicator i_(1, 5) to determine, from the full basis set, N′ basesincluded in the intermediate basis set (IntS) that are common among theplurality of v layers, and uses the received indicator i_(1, 6, l) todetermine, from the intermediate basis set, M_(l) bases included in thebasis subset for each layer l of the plurality of v layers.

The full basis set comprises N₃ bases, and wherein N₃, N′, and M_(l) arepositive integers; M_(l)<N₃ when the condition is satisfied andM_(l)<N′<N₃ when the condition is not satisfied; l∈{1, . . . , v}; andv≥1 is a rank value.

In one embodiment, when a value of N₃ is less than or equal to nineteen(N₃≤19), the condition is satisfied; and when the value of N₃ is greaterthan nineteen (N₃>19), the condition is not satisfied.

In one embodiment, one of the indices of the M_(l) bases included in thebasis subset is fixed to zero for each layer l of the plurality of vlayers.

In one embodiment, the indicator i_(1,6, l) indicates the indices of theremaining M_(l)−1 bases included in the basis subset for each layer l ofthe plurality of v layers, wherein a payload of the indicatori_(1, 6, l) is

$\left\lceil {\log_{2}\begin{pmatrix}{N_{3} - 1} \\{M_{l} - 1}\end{pmatrix}} \right\rceil\mspace{14mu}{bits}$

when the condition is satisfied and

$\left\lceil {\log_{2}\begin{pmatrix}{N^{\prime} - 1} \\{M_{l} - 1}\end{pmatrix}} \right\rceil\mspace{14mu}{bits}$

bits when the condition is not satisfied, and ┌ ┐ is a ceiling function.

In one embodiment, when the condition is not satisfied, the indicatori_(1, 5) indicates an initial basis index (M_(initial)) of theintermediate basis set (IntS), which is determined asIntS={(M_(initial)+i) mod N₃, i=0, 1, . . . , N′−1}, where mod is amodulo function.

In one embodiment, the transceiver is further configured to receive achannel state information (CSI) report from the UE; and the CSI reportincludes a pre-coding matrix indicator (PMI), the PMI including theindicator i_(1, 6, l) for each layer l of the plurality of v layers, andbased on the condition not being satisfied, the indicator i_(1, 5).

In one embodiment, the full basis set comprises a set of discreteFourier transform (DFT) vectors:

${w_{n} = \begin{bmatrix}1 & e^{j\frac{2\pi n}{N_{3}}} & e^{2j\frac{2\pi n}{N_{3}}} & \ldots & e^{{({N_{3} - 1})}j\frac{2\pi n}{N_{3}}}\end{bmatrix}},$

where n=0, 1, . . . , N₃−1.

In one embodiment, a value of N′ is such that N′=2M_(l).

Although the present disclosure has been described with an exemplaryembodiment, various changes and modifications may be suggested to oneskilled in the art. It is intended that the present disclosure encompasssuch changes and modifications as fall within the scope of the appendedclaims. None of the description in this application should be read asimplying that any particular element, step, or function is an essentialelement that must be included in the claims scope. The scope of patentedsubject matter is defined by the claims.

What is claimed is:
 1. A user equipment (UE), the UE comprising: atransceiver configured to: receive a configuration, the configurationincluding information about a set of N basis vectors; and a processoroperably coupled to the transceiver, the processor configured to:identify the set of N basis vectors; select, for each layer l, M basisvectors from the set of N basis vectors; and determine a channel stateinformation (CSI) report including, for each layer l, an indicatorindicating the selected M basis vectors, wherein the transceiver isfurther configured to transmit the CSI report including, for each layerl, the indicator indicating the selected M basis vectors, wherein M andN are integers and M<N, and wherein l∈{1, . . . , v}, where v is anumber of layers the CSI report corresponds to.
 2. The UE of claim 1,wherein the set of N basis vectors is a window of N consecutive basisvectors whose indices are given by mod(M_(init)+n, N₃), where n=0, 1, .. . , N−1.
 3. The UE of claim 2, wherein M_(init)=0 and the indices aregiven by {0, 1, . . . , N−1}.
 4. The UE of claim 3, wherein theinformation corresponds to a value of N.
 5. The UE of claim 1,6whereinfor each layer l, one of the selected M basis vectors has index n=0, andthe indicator indicates the remaining M−1 basis vectors.
 6. The UE ofclaim 5, wherein each indicator has a payload${\left\lceil {\log_{2}\begin{pmatrix}{N - 1} \\{M - 1}\end{pmatrix}} \right\rceil\mspace{14mu}{bits}},$ and is a component ofa pre-coding matrix indicator (PMI), wherein ┌ ┐ is a ceiling function.7. The UE of claim 1, wherein each basis vector in the set of basisvectors is a discrete Fourier transform (DFT) vector${w_{n} = \begin{bmatrix}1 & e^{j\frac{2\pi n}{N_{3}}} & e^{2j\frac{2\pi n}{N_{3}}} & \ldots & e^{{({N_{3} - 1})}j\frac{2\pi n}{N_{3}}}\end{bmatrix}},$ where n is an index of the basis vector, and N₃ is alength of the basis vector.
 8. A base station (BS) comprising: aprocessor configured to: generate a configuration, the configurationincluding information about a set of N basis vectors; and a transceiveroperably coupled to the processor, the transceiver configured to:transmit the configuration; and receive a channel state information(CSI) report including, for each layer l, an indicator indicating Mselected basis vectors, wherein the M selected basis vectors areselected, for each layer l, from the set of N basis vectors, wherein Mand N are integers and M<N, and wherein l∈{1, . . . , v}, where v is anumber of layers the CSI report corresponds to.
 9. The BS of claim 8,wherein the set of N basis vectors is a window of N consecutive basisvectors whose indices are given by mod(M_(init)+n, N₃), where n=0, 1, .. . , N−1.
 10. The BS of claim 9, wherein M_(init)=0 and the indices aregiven by {0, 1, . . . , N−1}.
 11. The BS of claim 10, wherein theinformation corresponds to a value of N.
 12. The BS of claim 8, whereinfor each layer l, one of the selected M basis vectors has index n=0, andthe indicator indicates the remaining M−1 basis vectors.
 13. The BS ofclaim 12, wherein each indicator has a payload${\left\lceil {\log_{2}\begin{pmatrix}{N - 1} \\{M - 1}\end{pmatrix}} \right\rceil\mspace{14mu}{bits}},$ and is a component ofa pre-coding matrix indicator (PMI), wherein ┌ ┐ is a ceiling function.14. The BS of claim 8, wherein each basis vector in the set of basisvectors is a discrete Fourier transform (DFT) vector${w_{n} = \begin{bmatrix}1 & e^{j\frac{2\pi n}{N_{3}}} & e^{2j\frac{2\pi n}{N_{3}}} & \ldots & e^{{({N_{3} - 1})}j\frac{2\pi n}{N_{3}}}\end{bmatrix}},$ where n is an index of the basis vector, and N₃ is alength of the basis vector.
 15. A method for operating a user equipment(UE), the method comprising: receiving a configuration, theconfiguration including information about a set of N basis vectors;identifying the set of N basis vectors; selecting, for each layer l, Mbasis vectors from the set of N basis vectors; determining a channelstate information (CSI) report including, for each layer l, an indicatorindicating the selected M basis vectors; and transmitting the CSI reportincluding, for each layer l, the indicator indicating the selected Mbasis vectors, wherein M and N are integers and M<N, and wherein l∈{1, .. . , v}, where v is a number of layers the CSI report corresponds to.16. The method of claim 15, wherein the set of N basis vectors is awindow of N consecutive basis vectors whose indices are given bymod(M_(init)+n, N₃), where n=0, 1, . . . , N−1.
 17. The method of claim16, wherein M_(inis)=0 and the indices are given by {0, 1, . . . , N−1}.18. The method of claim 17, wherein the information corresponds to avalue of N.
 19. The method of claim 15, wherein for each layer l, one ofthe selected M basis vectors has index n=0, and the indicator indicatesthe remaining M−1 basis vectors.
 20. The method of claim 19, whereineach indicator has a payload ${\left\lceil {\log_{2}\begin{pmatrix}{N - 1} \\{M - 1}\end{pmatrix}} \right\rceil\mspace{14mu}{bits}},$ and is a component ofa pre-coding matrix indicator (PMI), wherein ┌ ┐ is a ceiling function.